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# 15 Filter Effects

### Contents

## 15.1 Introduction

This chapter describes SVG's declarative filter effects feature set, which when combined with the 2D power of SVG can describe much of the common artwork on the Web in such a way that client-side generation and alteration can be performed easily.

A filter effect consists of a series of graphics operations that are applied to a given source graphic to produce a modified graphical result. The result of the filter effect is rendered to the target device instead of the original source graphic. The following illustrates the process:

View this example as SVG (SVG-enabled browsers only)

Filter effects are defined by 'filter' elements. To apply a filter effect to a graphics element or a container element, you set the value of the 'filter' property on the given element such that it references the filter effect.

Each 'filter' element contains a set of filter primitives as its children. Each filter primitive performs a single fundamental graphical operation (e.g., a blur or a lighting effect) on one or more inputs, producing a graphical result. Because most of the filter primitives represent some form of image processing, in most cases the output from a filter primitive is a single RGBA image.

The original source graphic or the result from a filter primitive can be used as input into one or more other filter primitives. A common application is to use the source graphic multiple times. For example, a simple filter could replace one graphic by two by adding a black copy of original source graphic offset to create a drop shadow. In effect, there are now two layers of graphics, both with the same original source graphics.

When applied to grouping elements such as 'g', the 'filter' property applies to the contents of the group as a whole. The group's children do not render to the screen directly; instead, the graphics commands necessary to render the children are stored temporarily. Typically, the graphics commands are executed as part of the processing of the referenced 'filter' element via use of the keywords SourceGraphic or SourceAlpha. Filter effects can be applied to grouping elements with no content (e.g., an empty 'g' element), in which case the SourceGraphic or SourceAlpha consist of a fully transparent rectangle that is the size of the filter effects region.

## 15.2 An example

The following shows an example of a filter effect.

Example filters01 - introducing filter effects.

    <?xml version="1.0"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20001102//EN"
                  "http://www.w3.org/TR/2000/CR-SVG-20001102/DTD/svg-20001102.dtd">
    <svg width="7.5cm" height="5cm" viewBox="0 0 200 120">
      <title>Example filters01.svg - introducing filter effects</title>
      <desc>An example which combines multiple filter primitives
            to produce a 3D lighting effect on a graphic consisting
            of the string "SVG" sitting on top of oval filled in red
            and surrounded by an oval outlined in red.</desc>
      <defs>
        <filter id="MyFilter">
          <feGaussianBlur in="SourceAlpha" stdDeviation="4" result="blur"/>
          <feOffset in="blur" dx="4" dy="4" result="offsetBlur"/>
          <feSpecularLighting in="blur" surfaceScale="5" specularConstant="1"
                              specularExponent="10" style="lighting-color:white"
                              result="specOut">
            <fePointLight x="-5000" y="-10000" z="20000"/>
          </feSpecularLighting>
          <feComposite in="specOut" in2="SourceAlpha" operator="in" result="specOut"/>
          <feComposite in="SourceGraphic" in2="specOut" operator="arithmetic"
                       k1="0" k2="1" k3="1" k4="0" result="litPaint"/>
          <feMerge>
            <feMergeNode in="offsetBlur"/>
            <feMergeNode in="litPaint"/>
          </feMerge>
        </filter>
      </defs>
      <rect x="1" y="1" width="198" height="118" style="fill:#888888; stroke:blue"/>
      <g style="filter:url(#MyFilter)">
    	  <g>
          <path style="fill:none; stroke:#D90000; stroke-width:10"
                d="M50,90 C0,90 0,30 50,30 L150,30 C200,30 200,90 150,90 z" />
          <path style="fill:#D90000"
                d="M60,80 C30,80 30,40 60,40 L140,40 C170,40 170,80 140,80 z" />
          <g style="fill:#FFFFFF; stroke:black; font-size:45; font-family:Verdana">
            <text x="52" y="76">SVG</text>
          </g>
        </g>
      </g>
    </svg>

Example filters01

View this example as SVG (SVG-enabled browsers only)

The filter effect used in the example above is repeated here with reference numbers in the left column before each of the six filter primitives:

    1
    2
    3

    4
    5

    6
    <filter id="MyFilter">
      <desc>Produces a 3D lighting effect.</desc>
      <feGaussianBlur in="SourceAlpha" stdDeviation="4" result="blur"/>
      <feOffset in="blur" dx="4" dy="4" result="offsetBlur"/>
      <feSpecularLighting in="blur" surfaceScale="5" specularConstant="1"
                          specularExponent="10" style="lighting-color:white"
                          result="specOut">
        <fePointLight x="-5000" y="-10000" z="20000"/>
      </feSpecularLighting>
      <feComposite in="specOut" in2="SourceAlpha" operator="in" result="specOut"/>
      <feComposite in="SourceGraphic" in2="specOut" operator="arithmetic"
                   k1="0" k2="1" k3="1" k4="0" result="litPaint"/>
      <feMerge>
        <feMergeNode in="offsetBlur"/>
        <feMergeNode in="litPaint"/>
      </feMerge>
    </filter>

The following pictures show the intermediate image results from each of the six filter elements:

Source graphic |  | After filter primitive 1 |  | After filter primitive 2 |  | After filter primitive 3
|  | After filter primitive 4 |  | After filter primitive 5 |  | After filter primitive 6

1. Filter primitive 'feGaussianBlur' takes input SourceAlpha, which is the alpha channel of the source graphic. The result is stored in a temporary buffer named "blur". Note that "blur" is used as input to both filter primitives 2 and 3.
2. Filter primitive 'feOffset' takes buffer "blur", shifts the result in a positive direction in both x and y, and creates a new buffer named "offsetBlur". The effect is that of a drop shadow.
3. Filter primitive 'feSpecularLighting', uses buffer "blur" as a model of a surface elevation and generates a lighting effect from a single point source. The result is stored in buffer "specOut".
4. Filter primitive 'feComposite' masks out the result of filter primitive 3 by the original source graphics alpha channel so that the intermediate result is no bigger than the original source graphic.

5. Filter primitive 'feComposite' composites the result of the specular lighting with the original source graphic.

6. Filter primitive 'feMerge' composites two layers together. The lower layer consists of the drop shadow result from filter primitive 2. The upper layer consists of the specular lighting result from filter primitive 5.

## 15.3 The 'filter' element

The description of the 'filter' element follows:

    <!ENTITY % filterExt "" >
    <!ELEMENT filter (%descTitleMetadata;,(feBlend|feFlood|
      feColorMatrix|feComponentTransfer|
      feComposite|feConvolveMatrix|feDiffuseLighting|feDisplacementMap|
      feGaussianBlur|feImage|feMerge|
      feMorphology|feOffset|feSpecularLighting|
      feTile|feTurbulence|
      animate|set
      %filterExt;)*) >
    <!ATTLIST filter
      %stdAttrs;
      %xlinkRefAttrs;
      xlink:href %URI; #IMPLIED
      %langSpaceAttrs;
      externalResourcesRequired %Boolean; #IMPLIED
      class %ClassList; #IMPLIED
      style %StyleSheet; #IMPLIED
      %PresentationAttributes-All;
      filterUnits (userSpaceOnUse | objectBoundingBox) #IMPLIED
      primitiveUnits (userSpaceOnUse | objectBoundingBox) #IMPLIED
      x %Coordinate; #IMPLIED
      y %Coordinate; #IMPLIED
      width %Length; #IMPLIED
      height %Length; #IMPLIED
      filterRes CDATA #IMPLIED >

Attribute definitions:

filterUnits = "userSpaceOnUse | objectBoundingBox"
  See Filter effects region.
primitiveUnits = "userSpaceOnUse | objectBoundingBox"
  Specifies the coordinate system for the various length values within the filter primitives.
  If primitiveUnits="userSpaceOnUse", any length values within the filter definitions represent values in the current user coordinate system in place at the time when the 'filter' element is referenced (i.e., the user coordinate system for the element referencing the 'filter' element via a 'filter' property).
  If primitiveUnits="objectBoundingBox", then any length values within the filter definitions represent fractions or percentages of the bounding box on the referencing element (see Object bounding box units).
  If attribute primitiveUnits is not specified, then the effect is as if a value of userSpaceOnUse were specified.
  Animatable: yes.
x = "x-coordinate"
  See Filter effects region.
y = "y-coordinate"
  See Filter effects region.
width = "length"
  See Filter effects region.
height = "length"
  See Filter effects region.
filterRes = "<number> [<number>]"
  See Filter effects region.
xlink:href = "<uri>"
  A URI reference to another 'filter' element within the current SVG document fragment. Any attributes which are defined on the referenced 'filter' element which are not defined on this element are inherited by this element. If this element has no defined filter nodes, and the referenced element has defined filter nodes (possibly due to its own href attribute), then this element inherits the filter nodes defined from the referenced 'filter' element. Inheritance can be indirect to an arbitrary level; thus, if the referenced 'filter' element inherits attributes or its filter node specification due to its own href attribute, then the current element can inherit those attributes or filter node specifications.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;, %langSpaceAttrs;, %xlinkRefAttrs; externalResourcesRequired, %PresentationAttributes-All;.

## 15.4 The 'filter' property

The description of the 'filter' property is as follows:

'filter'

  Value: | <uri> | none | inherit
  Initial: | none
  Applies to: | graphics and container elements
  Inherited: | no
  Percentages: | N/A
  Media: | visual
  Animatable: | yes

<uri>
  A URI reference to a 'filter' element which defines the filter effects that shall be applied to this element.
none
  Do not apply any filter effects to this element.

## 15.5 Filter effects region

A 'filter' element can define a region on the canvas on which a given filter effect applies and can provide a resolution for any intermediate continuous tone images used to process any raster-based filter primitives. The 'filter' element has the following attributes which work together to define the filter effects region:

- filterUnits={ userSpaceOnUse | objectBoundingBox }.
  Defines the coordinate system for attributes x, y, width, height.
  If filterUnits="userSpaceOnUse", x, y, width, height represent values in the current user coordinate system in place at the time when the 'filter' element is referenced (i.e., the user coordinate system for the element referencing the 'filter' element via a 'filter' property).
  If filterUnits="objectBoundingBox", then x, y, width, height represent fractions or percentages of the bounding box on the referencing element (see Object bounding box units).
  If attribute filterUnits is not specified, then the effect is as if a value of objectBoundingBox were specified.
  Animatable: yes.
- x, y, width, height, which indicate the rectangle for the largest possible offscreen buffer. The coordinate system for these attributes depends on the value for attribute filterUnits.
  Negative values for width or height are an error (see Error processing). Zero values disable rendering of the element which referenced the filter.
  If x or y is not specified, the effect is as if a value of "-10%" were specified.
  If width or height is not specified, the effect is as if a value of "120%" were specified.
  Animatable: yes.
- filterRes (which has the form `x-pixels [y-pixels])` indicates the width and height of the intermediate images in pixels. If not provided, then a reasonable default resolution appropriate for the target device will be used. (For displays, an appropriate display resolution, preferably the current display's pixel resolution, is the default. For printing, an appropriate common printer resolution, such as 400dpi, is the default.)
  Negative values are an error (see Error processing). Zero values disable rendering of the element which referenced the filter.
  Animatable: yes.

For performance reasons on display devices, it is recommended that the filter effect region is designed to match pixel-for-pixel with the background.

It is often necessary to provide padding space because the filter effect might impact bits slightly outside the tight-fitting bounding box on a given object. For these purposes, it is possible to provide negative percentage values for x, y and percentages values greater than 100% for width, height. For example, x="-10%" y="-10%" width="120%" height="120%".

## 15.6 Accessing the background image

Two possible pseudo input images for filter effects are BackgroundImage and BackgroundAlpha, which each represent an image snapshot of the canvas under the filter region at the time that the <filter> element is invoked. BackgroundImage represents both the color values and alpha channel of the canvas (i.e., RGBA pixel values), whereas BackgroundAlpha represents only the alpha channel.

Implementations of SVG user agents often will need to maintain supplemental background image buffers in order to support the BackgroundImage and BackgroundAlpha pseudo input images. Sometimes, the background image buffers will contain an in-memory copy of the accumulated painting operations on the current canvas.

Because in-memory image buffers can take up significant system resources, SVG content must explicitly indicate to the SVG user agent that the document needs access to the background image before BackgroundImage and BackgroundAlpha pseudo input images can be used. The property which enables access to the background image is 'enable-background':

'enable-background'

  Value: | accumulate | new [ <x> <y> <width> <height> ] | inherit
  Initial: | accumulate
  Applies to: | container elements
  Inherited: | no
  Percentages: | N/A
  Media: | visual
  Animatable: | no

'enable-background' is only applicable to container elements and specifies how the SVG user agents manages the accumulation of the background image.

A value of new indicates two things:

- It enables the ability of children of the current container element to access the background image.
- It indicates that a new (i.e., initially fully transparent) background image canvas is established and that (in effect) all children of the current container element shall be rendered into the new background image canvas in addition to being rendered onto the target device.

A meaning of enable-background: accumulate (the initial/default value) depends on context:

- If an ancestor container element has a property value of 'enable-background:new', then all graphics elements within the current container element are rendered both onto the parent container element's background image canvas and onto the target device.
- Otherwise, there is no current background image canvas, so it is only necessary to render graphics elements onto the target device. (No need to render to the background image canvas.)

If a filter effect specifies either the BackgroundImage or the BackgroundAlpha pseudo input images and no ancestor container element has a property value of 'enable-background:new', then the background image request is technically in error. Processing will proceed without interruption (i.e., no error message) and a fully transparent image shall be provided in response to the request.

The optional <x>,<y>,<width>,<height> parameters on the new value indicate the subregion of user space where access to the background image is allowed to happen. These parameters enable the SVG user agent potentially to allocate smaller temporary image buffers than the default values, which might require the SVG user agent to allocate buffers as large as the current viewport. Thus, the values <x>,<y>,<width>,<height> act as a clipping rectangle on the background image canvas. Negative values for <width> or <height> are an error (see Error processing). If more than zero but less than four of the values <x>,<y>,<width> and <height> are specified or if zero values are specified for <width> or <height>, BackgroundImage and BackgroundAlpha are processed as if background image processing were not enabled.

## 15.7 Filter primitives overview

### 15.7.1 Overview

This section describes the various filter primtives that can be assembed to achieve a particular filter effect.

Unless otherwise stated, all image filters operate on linear premultiplied RGBA samples. Filters which work more naturally on non-premultiplied data (feColorMatrix and feComponentTransfer) will temporarily undo and redo premultiplication as specified. All raster effect filtering operations take 1 to N input RGBA images, additional attributes as parameters, and produce a single output RGBA image.

The RGBA result from each filter primitive will be clamped into the allowable ranges for colors and opacity values. Thus, for example, the result from a given filter primitives will have any negative color values or opacity values adjusted up to color/opacity of zero.

### 15.7.2 Common attributes

The following attributes are available for most of the filter primitives:

    <!ENTITY % filter_primitive_attributes
      "x %Coordinate; #IMPLIED
       y %Coordinate; #IMPLIED
       width %Length; #IMPLIED
       height %Length; #IMPLIED
       result CDATA #IMPLIED" >

    <!ENTITY % filter_primitive_attributes_with_in
      "%filter_primitive_attributes;
       in CDATA #IMPLIED">

Attribute definitions:

x = "<coordinate>"
  The minimum x coordinate for the subregion which restricts calculation and rendering of the given filter primitive. See filter primitive subregion.
  Animatable: yes.
y = "<coordinate>"
  The minimum y coordinate for the subregion which restricts calculation and rendering of the given filter primitive. See filter primitive subregion. Animatable: yes.
width = "<length>"
  The width of the subregion which restricts calculation and rendering of the given filter primitive. See filter primitive subregion.
  A negative value is an error (see Error processing). A value of zero disables the effect of the given filter primitive (i.e., the result is a fully transparent image).
  Animatable: yes.
height = "<length>"
  The height of the subregion which restricts calculation and rendering of the given filter primitive. See filter primitive subregion.
  A negative value is an error (see Error processing). A value of zero disables the effect of the given filter primitive (i.e., the result is a fully transparent image).
  Animatable: yes.
result = "<filter-primitive-reference>"
  Assigned name for this filter primitive. If supplied, then graphics that result from processing this filter primitive can be referenced by an in attribute on a subsequent filter primitive within the same 'filter' element. If no value is provided, the output will only be available for re-use as the implicit input into the next filter primitive if that filter primitive provides no value for its in attribute.
  Note that a <filter-primitive-reference> is not an XML ID; instead, a <filter-primitive-reference> is only meaningful within a given 'filter' element and thus have only local scope. It is legal for the same <filter-primitive-reference> to appear multiple times within the same 'filter' element. When referenced, the <filter-primitive-reference> will use the closest preceding filter primitive with the given result.
  Animatable: yes.
in = "SourceGraphic | SourceAlpha | BackgroundImage | BackgroundAlpha | FillPaint | StrokePaint | <filter-primitive-reference>"
  Identifies input for the given filter primitive. The value can be either one of six keywords or can be a string which matches a previous result attribute value within the same 'filter' element. If no value is provided and this is the first filter primitive, then this filter primitive will use SourceGraphic as its input. If no value is provided and this is a subsequent filter primitive, then this filter primitive will use the result from the previous filter primitive as its input.
  If the value for result appears multiple times within a given 'filter' element, then a reference to that result will use the closest preceding filter primitive with the given value for attribute result. Forward references to results are an error.
  Definitions for the six keywords:
  SourceGraphic
    This keyword represents the graphics elements that were the original input into the 'filter' element. For raster effects filter primitives, the graphics elements will be rasterized into an initially clear RGBA raster in image space. Pixels left untouched by the original graphic will be left clear. The image is specified to be rendered in linear RGBA pixels. The alpha channel of this image captures any anti-aliasing specified by SVG. (Since the raster is linear, the alpha channel of this image will represent the exact percent coverage of each pixel.)
  SourceAlpha
    This keyword represents the graphics elements that were the original input into the 'filter' element. SourceAlpha has all of the same rules as SourceGraphic except that only the alpha channel is used. The input image is an RGBA image consisting of implicitly black color values for the RGB channels, but whose alpha channel is the same as SourceGraphic. If this option is used, then some implementations might need to rasterize the graphics elements in order to extract the alpha channel.
  BackgroundImage
    This keyword represents an image snapshot of the canvas under the filter region at the time that the 'filter' element was invoked. See Accessing the background image.
  BackgroundAlpha
    Same as BackgroundImage except only the alpha channel is used. See SourceAlpha and Accessing the background image.
  FillPaint
    This keyword represents the value of the 'fill' property on the target element for the filter effect. The FillPaint image has conceptually infinite extent. Frequently this image is opaque everywhere, but it might not be if the "paint" itself has alpha, as in the case of an alpha gradient or transparent pattern.
  StrokePaint
    This keyword represents the value of the 'stroke' property on the target element for the filter effect. The StrokePaint image has conceptually infinite extent. Frequently this image is opaque everywhere, but it might not be if the "paint" itself has alpha, as in the case of an alpha gradient or transparent pattern.
  Animatable: yes.

### 15.7.3 Filter primitive subregion

All filter primitives have attributes x, y, width and height which identify a subregion which restricts calculation and rendering of the given filter primitive. These attributes are defined according to the same rules as other filter primitives' coordinate and length attributes.

x, y, width and height default to the union (i.e., tightest fitting bounding box) of the subregions defined for all referenced nodes. If there are no referenced nodes (e.g., for 'feImage' or 'feTurbulence', which have no specified value for in, or if in="SourceGraphic") or for 'feTile' (which is special), the default subregion is 0%,0%,100%,100%, where percentages are relative to the dimensions of the filter region.

x, y, width and height act as a hard clip clipping rectangle.

All intermediate offscreens are defined to not exceed the intersection of x, y, width and height with the filter region. The filter region and any of the x, y, width and height subregions are to be set up such that all offscreens are made big enough to accommodate any pixels which even partly intersect with either the filter region or the x,y,width,height subregions.

'feImage' scales the referenced image to fit exactly into the subregion specified by x, y, width and height.

'feTile' references a previous filter primitive and then stitches the tiles together based on the x, y, width and height values of the referenced filter primitive.

## 15.8 Light source elements and properties

### 15.8.1 Introduction

The following sections define the elements that define a light source, 'feDistantLight', 'fePointLight' and 'feSpotLight', and property 'lighting-color', which defines the color of the light.

### 15.8.2 Light source 'feDistantLight'

    <!ELEMENT feDistantLight (animate|set)* >
    <!ATTLIST feDistantLight
      %stdAttrs;
      azimuth %Number; #IMPLIED
      elevation %Number; #IMPLIED >

Attribute definitions:

azimuth = "<number>"
  Direction angle for the light source on the XY plane, in degrees.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.
elevation = "<number>"
  Direction angle for the light source on the YZ plane, in degrees.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;.

### 15.8.3 Light source 'fePointLight'

    <!ELEMENT fePointLight (animate|set)* >
    <!ATTLIST fePointLight
      %stdAttrs;
      x %Number; #IMPLIED
      y %Number; #IMPLIED
      z %Number; #IMPLIED >

Attribute definitions:

x = "<number>"
  X location for the light source.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.
y = "<number>"
  Y location for the light source.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.
z = "<number>"
  Z location for the light source.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;.

### 15.8.4 Light source 'feSpotLight'

    <!ELEMENT feSpotLight (animate|set)* >
    <!ATTLIST feSpotLight
      %stdAttrs;
      x %Number; #IMPLIED
      y %Number; #IMPLIED
      z %Number; #IMPLIED
      pointsAtX %Number; #IMPLIED
      pointsAtY %Number; #IMPLIED
      pointsAtZ %Number; #IMPLIED
      specularExponent %Number; #IMPLIED
      limitingConeAngle %Number; #IMPLIED >

Attribute definitions:

x = "<number>"
  X location for the light source.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.
y = "<number>"
  Y location for the light source.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.
z = "<number>"
  Z location for the light source.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.
pointsAtX = "<number>"
  X location of the point at which the light source is pointing.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.
pointsAtY = "<number>"
  Y location of the point at which the light source is pointing.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.
pointsAtZ = "<number>"
  Z location of the point at which the light source is pointing.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.
specularExponent = "<number>"
  Exponent value controlling the focus for the light source.
  If the attribute is not specified, then the effect is as if a value of 1 were specified.
  Animatable: yes.
limitingConeAngle = "<number>"
  A limiting cone which restricts the region where the light is projected. No light is projected outside the cone. limitingConeAngle represents the angle between the spot light axis (i.e. the axis between the light source and the point to which it is pointing at) and the spot light cone. User agents should apply a smoothing technique such as anti-aliasing at the boundary of the cone.
  If no value is specified, then no limiting cone will be applied.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;.

### 15.8.5 The 'lighting-color' property

The 'lighting-color' property defines the color of the light source for filter primitives 'feDiffuseLighting' and 'feSpecularLighting'.

'lighting-color'

  Value: | currentColor | <color> [icc-color(<name>[,<icccolorvalue>]*)] | inherit
  Initial: | white
  Applies to: | 'feDiffuseLighting' and 'feSpecularLighting' elements
  Inherited: | no
  Percentages: | N/A
  Media: | visual
  Animatable: | yes

## 15.9 Filter primitive 'feBlend'

This filter composites two objects together using commonly used imaging software blending modes. It performs a pixel-wise combination of two input images.

    <!ELEMENT feBlend (animate|set)* >
    <!ATTLIST feBlend
      %stdAttrs;
      %filter_primitive_attributes_with_in;
      in2 CDATA #REQUIRED
      mode (normal | multiply | screen | darken | lighten) "normal" >

Attribute definitions:

mode = "normal | multiply | screen | darken | lighten"
  One of the image blending modes (see table below). Default is: normal.
  Animatable: yes.
in2 = "(see in attribute)"
  The second input image to the blending operation. This attribute can take on the same values as the in attribute.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;, %filter_primitive_attributes_with_in;.

For all feBlend modes, the result opacity is computed as follows:

    qr = 1 - (1-qa)*(1-qb)

For the compositing formulas below, the following definitions apply:

    cr = Result color (RGB) - premultiplied
    qa = Opacity value at a given pixel for image A
    qb = Opacity value at a given pixel for image B
    ca = Color (RGB) at a given pixel for image A - premultiplied
    cb = Color (RGB) at a given pixel for image B - premultiplied

The following table provides the list of available image blending modes:

Image Blending Mode | Formula for computing result color
normal | cr = (1 - qa) * cb + ca
multiply | cr = (1-qa)*cb + (1-qb)*ca + ca*cb
screen | cr = cb + ca - ca * cb
darken | cr = Min ((1 - qa) * cb + ca, (1 - qb) * ca + cb)
lighten | cr = Max ((1 - qa) * cb + ca, (1 - qb) * ca + cb)

Example feBlend shows examples of the five blend modes.

    <?xml version="1.0"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20001102//EN"
              "http://www.w3.org/TR/2000/CR-SVG-20001102/DTD/svg-20001102.dtd">
    <svg width="5cm" height="5cm" viewBox="0 0 500 500">
      <title>Example feBlend - Examples of feBlend modes</title>
      <desc>Five text strings blended into a gradient,
            with one text string for each of the five feBlend modes.</desc>
      <defs>
        <linearGradient id="MyGradient" gradientUnits="userSpaceOnUse"
                x1="100" y1="0" x2="300" y2="0">
          <stop offset="0" style="stop-color:#000000"/>
          <stop offset=".33" style="stop-color:#ffffff"/>
          <stop offset=".67" style="stop-color:#ff0000"/>
          <stop offset="1" style="stop-color:#808080"/>
        </linearGradient>
        <filter id="Normal">
          <feBlend mode="normal" in2="BackgroundImage" in="SourceGraphic"/>
        </filter>
        <filter id="Multiply">
          <feBlend mode="multiply" in2="BackgroundImage" in="SourceGraphic"/>
        </filter>
        <filter id="Screen">
          <feBlend mode="screen" in2="BackgroundImage" in="SourceGraphic"/>
        </filter>
        <filter id="Darken">
          <feBlend mode="darken" in2="BackgroundImage" in="SourceGraphic"/>
        </filter>
        <filter id="Lighten">
          <feBlend mode="lighten" in2="BackgroundImage" in="SourceGraphic"/>
        </filter>
      </defs>
      <rect style="fill:none; stroke:blue"
            x="1" y="1" width="498" height="498"/>
      <g style="enable-background: new">
        <rect x="100" y="20" width="300" height="460" style="fill:url(#MyGradient)"/>
        <g style="font-family:Verdana; font-size:75; fill:#888888; fill-opacity:.6">
          <text x="50" y="90" style="filter:url(#Normal)">Normal</text>
          <text x="50" y="180" style="filter:url(#Multiply)">Multiply</text>
          <text x="50" y="270" style="filter:url(#Screen)">Screen</text>
          <text x="50" y="360" style="filter:url(#Darken)">Darken</text>
          <text x="50" y="450" style="filter:url(#Lighten)">Lighten</text>
        </g>
      </g>
    </svg>

Example feBlend

View this example as SVG (SVG-enabled browsers only)

## 15.10 Filter primitive 'feColorMatrix'

This filter applies a matrix transformation:

    | R' |     | a00 a01 a02 a03 a04 |   | R |

    | G' |     | a10 a11 a12 a13 a14 |   | G |

    | B' |  =  | a20 a21 a22 a23 a24 | * | B |

    | A' |     | a30 a31 a32 a33 a34 |   | A |

    | 1  |     |  0   0   0   0   1  |   | 1 |

on the RGBA color and alpha values of every pixel on the input graphics to produce a result with a new set of RGBA color and alpha values.

The calculations are performed on non-premultiplied color values. If the input graphics consists of premultiplied color values, those values are automatically converted into non-premultiplied color values for this operation.

These matrices often perform an identity mapping in the alpha channel. If that is the case, an implementation can avoid the costly undoing and redoing of the premultiplication for all pixels with A = 1.

    <!ELEMENT feColorMatrix (animate|set)* >
    <!ATTLIST feColorMatrix
      %stdAttrs;
      %filter_primitive_attributes_with_in;
      type (matrix | saturate | hueRotate | luminanceToAlpha) "matrix"
      values CDATA #IMPLIED >

Attribute definitions:

type = "matrix | saturate | hueRotate | luminanceToAlpha"
  Indicates the type of matrix operation. The keyword matrix indicates that a full 5x4 matrix of values will be provided. The other keywords represent convenience shortcuts to allow commonly used color operations to be performed without specifying a complete matrix.
  Animatable: yes.
values = "list of <number>s"
  The contents of values depends on the value of attribute type:
  - For type="matrix", values is a list of 20 matrix values (a00 a01 a02 a03 a04 a10 a11 ... a34), separated by whitespace and/or a comma. For example, the identity matrix could be expressed as:

        type="matrix"
        values="1 0 0 0 0  0 1 0 0 0  0 0 1 0 0  0 0 0 1 0"

  - For type="saturate", values is a single real number value (0 to 1) or one percentage value (e.g., 50%). A saturate operation is equivalent to the following matrix operation:

        | R' |     |0.213+0.787s  0.715-0.715s  0.072-0.072s 0  0 |   | R |

        | G' |     |0.213-0.213s  0.715+0.285s  0.072-0.072s 0  0 |   | G |

        | B' |  =  |0.213-0.213s  0.715-0.715s  0.072+0.928s 0  0 | * | B |

        | A' |     |           0            0             0  1  0 |   | A |

        | 1  |     |           0            0             0  0  1 |   | 1 |

  - For type="hueRotate", values is a single one real number value (degrees). A hueRotate operation is equivalent to the following matrix operation:

        | R' |     | a00  a01  a02  0  0 |   | R |

        | G' |     | a10  a11  a12  0  0 |   | G |

        | B' |  =  | a20  a21  a22  0  0 | * | B |

        | A' |     | 0    0    0    1  0 |   | A |

        | 1  |     | 0    0    0    0  1 |   | 1 |

    where the terms a00, a01, etc. are calculated as follows:

        | a01 a01 a02 |    [+0.213 +0.715 +0.072]
        | a10 a11 a12 | =  [+0.213 +0.715 +0.072] +
        | a20 a21 a22 |    [+0.213 +0.715 +0.072]

                                [+0.787 -0.715 -0.072]
        cos(hueRotate value) *  [-0.212 +0.285 -0.072] +
                                [-0.213 -0.715 +0.928]

                                [-0.213 -0.715+0.928]
        sin(hueRotate value) *  [+0.143 +0.140-0.283]
                                [-0.787 +0.715+0.072]

    Thus, the upper left term of the hue matrix turns out to be:

        .213 + cos(hueRotate value)*.787 - sin(hueRotate value)*.213

  - For type="luminanceToAlpha", values is not applicable. A luminanceToAlpha operation is equivalent to the following matrix operation:

           | R' |     |      0        0        0  0  0 |   | R |

           | G' |     |      0        0        0  0  0 |   | G |

           | B' |  =  |      0        0        0  0  0 | * | B |

           | A' |     | 0.2125   0.7154   0.0721  0  0 |   | A |

           | 1  |     |      0        0        0  0  1 |   | 1 |

  If the attribute is not specified, then the default behavior depends on the value of attribute type. If type="matrix", then this attribute defaults to the identity matrix. If type="saturate", then this attribute defaults to the value 1. If type="hueRotate", then this attribute defaults to the value 0.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;, %filter_primitive_attributes_with_in;.

Example feColorMatrix shows examples of the four types of feColorMatrix operations.

    <?xml version="1.0"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20001102//EN"
              "http://www.w3.org/TR/2000/CR-SVG-20001102/DTD/svg-20001102.dtd">
    <svg width="8cm" height="5cm" viewBox="0 0 800 500">
      <title>Example feColorMatrix - Examples of feColorMatrix operations</title>
      <desc>Five text strings showing the effects of feColorMatrix:
            an unfiltered text string acting as a reference,
            use of the feColorMatrix matrix option to convert to grayscale,
            use of the feColorMatrix saturate option,
            use of the feColorMatrix hueRotate option,
            and use of the feColorMatrix luminanceToAlpha option.</desc>
      <defs>
        <linearGradient id="MyGradient" gradientUnits="userSpaceOnUse"
                x1="100" y1="0" x2="500" y2="0">
          <stop offset="0" style="stop-color:#ff00ff"/>
          <stop offset=".33" style="stop-color:#88ff88"/>
          <stop offset=".67" style="stop-color:#2020ff"/>
          <stop offset="1" style="stop-color:#d00000"/>
        </linearGradient>
        <filter id="Matrix" filterUnits="objectBoundingBox"
                x="0%" y="0%" width="100%" height="100%">
          <feColorMatrix type="matrix" in="SourceGraphic"
               values=".33 .33 .33 0 0
                       .33 .33 .33 0 0
                       .33 .33 .33 0 0
                       .33 .33 .33 0 0"/>
        </filter>
        <filter id="Saturate40" filterUnits="objectBoundingBox"
                x="0%" y="0%" width="100%" height="100%">
          <feColorMatrix type="saturate" in="SourceGraphic" values="40%"/>
        </filter>
        <filter id="HueRotate90" filterUnits="objectBoundingBox"
                x="0%" y="0%" width="100%" height="100%">
          <feColorMatrix type="hueRotate" in="SourceGraphic" values="90"/>
        </filter>
        <filter id="LuminanceToAlpha" filterUnits="objectBoundingBox"
                x="0%" y="0%" width="100%" height="100%">
          <feColorMatrix type="luminanceToAlpha" in="SourceGraphic" result="a"/>
          <feComposite in="SourceGraphic" in2="a" operator="in" />
        </filter>
      </defs>
      <rect style="fill:none; stroke:blue"
            x="1" y="1" width="798" height="498"/>
      <g style="font-family:Verdana; font-size:75;
                font-weight:bold; fill:url(#MyGradient)">
        <rect x="100" y="0" width="500" height="20" />
        <text x="100" y="90">Unfiltered</text>
        <text x="100" y="190" style="filter:url(#Matrix)">Matrix</text>
        <text x="100" y="290" style="filter:url(#Saturate20)">Saturate</text>
        <text x="100" y="390" style="filter:url(#HueRotate90)">HueRotate</text>
        <text x="100" y="490" style="filter:url(#LuminanceToAlpha)">Luminance</text>
      </g>
    </svg>

Example feColorMatrix

View this example as SVG (SVG-enabled browsers only)

## 15.11 Filter primitive 'feComponentTransfer'

This filter primitive performs component-wise remapping of data as follows:

    R' = feFuncR( R )
    G' = feFuncG( G )
    B' = feFuncB( B )
    A' = feFuncA( A )

for every pixel. It allows operations like brightness adjustment, contrast adjustment, color balance or thresholding.

The calculations are performed on non-premultiplied color values. If the input graphics consists of premultiplied color values, those values are automatically converted into non-premultiplied color values for this operation. (Note that the undoing and redoing of the premultiplication can be avoided if feFuncA is the identity transform and all alpha values on the source graphic are set to 1.)

    <!ELEMENT feComponentTransfer (feFuncR?,feFuncG?,feFuncB?,feFuncA?) >
    <!ATTLIST feComponentTransfer
      %stdAttrs;
      %filter_primitive_attributes_with_in; >

    <!ENTITY % component_transfer_function_attributes
      "type (identity | table | discrete | linear | gamma) #REQUIRED
       tableValues CDATA #IMPLIED
       slope %Number; #IMPLIED
       intercept %Number; #IMPLIED
       amplitude %Number; #IMPLIED
       exponent %Number; #IMPLIED
       offset %Number; #IMPLIED" >

    <!ELEMENT feFuncR (animate|set)* >
    <!ATTLIST feFuncR
      %stdAttrs;
      %component_transfer_function_attributes; >

    <!ELEMENT feFuncG (animate|set)* >
    <!ATTLIST feFuncG
      %stdAttrs;
      %component_transfer_function_attributes; >

    <!ELEMENT feFuncB (animate|set)* >
    <!ATTLIST feFuncB
      %stdAttrs;
      %component_transfer_function_attributes; >

    <!ELEMENT feFuncA (animate|set)* >
    <!ATTLIST feFuncA
      %stdAttrs;
      %component_transfer_function_attributes; >

The specification of the transfer functions is defined by the sub-elements to 'feComponentTransfer':
  'feFuncR', transfer function for red component of the input graphic
  'feFuncG', transfer function for green component of the input graphic
  'feFuncB', transfer function for blue component of the input graphic
  'feFuncA', transfer function for alpha component of the input graphic

The attributes below apply to sub-elements 'feFuncR', 'feFuncG', 'feFuncB' and 'feFuncA' define the transfer functions.

Attribute definitions:

type = "identity | table | discrete | linear | gamma"

  Indicates the type of component transfer function. The type of function determines the applicability of the other attributes.

  - For identity:

        C' = C

  - For table, the function is defined by linear interpolation into a lookup table by attribute tableValues, which provides a list of n+1 values (i.e., v0 to vn) in order to identify n interpolation ranges. Interpolations use the following formula:

    k/N <= C < (k+1)/N => C' = vk + (C - k/N)*N * (vk+1 - vk)

  - For discrete, the function is defined by the step function defined by attribute tableValues, which provides a list of n values (i.e., v0 to vn-1) in order to identify a step function consisting of n steps. The step function is defined by the following formula:

    k/N <= C < (k+1)/N => C' = vk

  - For linear, the function is defined by the following linear equation:

    C' = slope * C + intercept

  - For gamma, the function is defined by the following exponential function:

    C' = amplitude * pow(C, exponent) + offset

  Animatable: yes.
tableValues = "(list of <number>s)"
  When type="table", the list of <number>s v0,v1,...vn, separated by white space and/or a comma, which define the lookup table. An empty list results in an identity transfer function.
  If the attribute is not specified, then the effect is as if an empty list were provided.
  Animatable: yes.
slope = "<number>"
  When type="linear", the slope of the linear function.
  If the attribute is not specified, then the effect is as if a value of 1 were specified.
  Animatable: yes.
intercept = "<number>"
  When type="linear", the intercept of the linear function.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.
amplitude = "<number>"
  When type="gamma", the amplitude of the gamma function.
  If the attribute is not specified, then the effect is as if a value of 1 were specified.
  Animatable: yes.
exponent = "<number>"
  When type="gamma", the exponent of the gamma function.
  If the attribute is not specified, then the effect is as if a value of 1 were specified.
  Animatable: yes.
offset = "<number>"
  When type="gamma", the offset of the gamma function.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;, %filter_primitive_attributes_with_in;.

Example feComponentTransfer shows examples of the four types of feComponentTransfer operations.

    <?xml version="1.0"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20001102//EN"
              "http://www.w3.org/TR/2000/CR-SVG-20001102/DTD/svg-20001102.dtd">
    <svg width="8cm" height="4cm" viewBox="0 0 800 400">
      <title>Example feComponentTransfer - Examples of feComponentTransfer operations</title>
      <desc>Four text strings showing the effects of feComponentTransfer:
            an identity function acting as a reference,
            use of the feComponentTransfer table option,
            use of the feComponentTransfer linear option,
            and use of the feComponentTransfer gamma option.</desc>
      <defs>
        <linearGradient id="MyGradient" gradientUnits="userSpaceOnUse"
                x1="100" y1="0" x2="600" y2="0">
          <stop offset="0" style="stop-color:#ff0000"/>
          <stop offset=".33" style="stop-color:#00ff00"/>
          <stop offset=".67" style="stop-color:#0000ff"/>
          <stop offset="1" style="stop-color:#000000"/>
        </linearGradient>
        <filter id="Identity" filterUnits="objectBoundingBox"
                x="0%" y="0%" width="100%" height="100%">
          <feComponentTransfer>
            <feFuncR type="identity"/>
            <feFuncG type="identity"/>
            <feFuncB type="identity"/>
            <feFuncA type="identity"/>
          </feComponentTransfer>
        </filter>
        <filter id="Table" filterUnits="objectBoundingBox"
                x="0%" y="0%" width="100%" height="100%">
          <feComponentTransfer>
            <feFuncR type="table" tableValues="0 0 1 1"/>
            <feFuncG type="table" tableValues="1 1 0 0"/>
            <feFuncB type="table" tableValues="0 1 1 0"/>
          </feComponentTransfer>
        </filter>
        <filter id="Linear" filterUnits="objectBoundingBox"
                x="0%" y="0%" width="100%" height="100%">
          <feComponentTransfer>
            <feFuncR type="linear" slope=".5" intercept=".25"/>
            <feFuncG type="linear" slope=".5" intercept="0"/>
            <feFuncB type="linear" slope=".5" intercept=".5"/>
          </feComponentTransfer>
        </filter>
        <filter id="Gamma" filterUnits="objectBoundingBox"
                x="0%" y="0%" width="100%" height="100%">
          <feComponentTransfer>
            <feFuncR type="gamma" amplitude="2" exponent="5" offset="0"/>
            <feFuncG type="gamma" amplitude="2" exponent="3" offset="0"/>
            <feFuncB type="gamma" amplitude="2" exponent="1" offset="0"/>
          </feComponentTransfer>
        </filter>
      </defs>
      <rect style="fill:none; stroke:blue"
            x="1" y="1" width="798" height="398"/>
      <g style="font-family:Verdana; font-size:75;
                font-weight:bold; fill:url(#MyGradient)">
        <rect x="100" y="0" width="600" height="20" />
        <text x="100" y="90">Identity</text>
        <text x="100" y="190" style="filter:url(#Table)">TableLookup</text>
        <text x="100" y="290" style="filter:url(#Linear)">LinearFunc</text>
        <text x="100" y="390" style="filter:url(#Gamma)">GammaFunc</text>
      </g>
    </svg>

Example feComponentTransfer

View this example as SVG (SVG-enabled browsers only)

## 15.12 Filter primitive 'feComposite'

This filter performs the combination of the two input images pixel-wise in image space using one of the Porter-Duff [PORTERDUFF] compositing operations: over, in, atop, out, xor. Additionally, a component-wise arithmetic operation (with the result clamped between [0..1]) can be applied.

The arithmetic operation is useful for combining the output from the 'feDiffuseLighting' and 'feSpecularLighting' filters with texture data. It is also useful for implementing dissolve. If the arithmetic operation is chosen, each result pixel is computed using the following formula:

    result = k1*i1*i2 + k2*i1 + k3*i2 + k4

For these operations, the extent of the resulting image can be affected. In other words, even if two images do not overlap in image space, the extent for over will essentially include the union of the extents of the two input images.

    <!ELEMENT feComposite (animate|set)* >
    <!ATTLIST feComposite
      %stdAttrs;
      %filter_primitive_attributes_with_in;
      in2 CDATA #REQUIRED
      operator (over | in | out | atop | xor | arithmetic) "over"
      k1 %Number; #IMPLIED
      k2 %Number; #IMPLIED
      k3 %Number; #IMPLIED
      k4 %Number; #IMPLIED >

Attribute definitions:

operator = "over | in | out | atop | xor | arithmetic"
  The compositing operation that is to be performed. All of the operator types except arithmetic match the correspond operation as described in [PORTERDUFF]. The arithmetic operator is described above.
  Animatable: yes.
k1 = "<number>"
  Only applicable if operator="arithmetic".
  If the attribute is not specified, the effect is as if a value of "0" were specified.
  Animatable: yes.
k2 = "<number>"
  Only applicable if operator="arithmetic".
  If the attribute is not specified, the effect is as if a value of "0" were specified.
  Animatable: yes.
k3 = "<number>"
  Only applicable if operator="arithmetic".
  If the attribute is not specified, the effect is as if a value of "0" were specified.
  Animatable: yes.
k4 = "<number>"
  Only applicable if operator="arithmetic".
  If the attribute is not specified, the effect is as if a value of "0" were specified.
  Animatable: yes.
in2 = "(see in attribute)"
  The second input image to the compositing operation. This attribute can take on the same values as the in attribute.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;, %filter_primitive_attributes_with_in;.

Example feComposite shows examples of the six types of feComposite operations. It also shows two different techniques to using the BackgroundImage as part of the compositing operation.

The first two rows render bluish triangles into the background. A filter is applied which composites reddish triangles into the bluish triangles using one of the compositing operations. The result from compositing is drawn onto an opaque white temporary surface, and then that result is written to the canvas. (The opaque white temporary surface obliterates the original bluish triangle.)

The last two rows apply the same compositing operations of reddish triangles into bluish triangles. However, the compositing result is directly blended into the canvas (the opaque white temporary surface technique is not used). In some cases, the results are different than when a temporary opaque white surface is used. The original bluish triangle from the background shines through wherever the compositing operation results in completed transparent pixel. In other cases, the result from compositing is blended into the bluish triangle, resulting in a different final color value.

    <?xml version="1.0"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20001102//EN"
              "http://www.w3.org/TR/2000/CR-SVG-20001102/DTD/svg-20001102.dtd">
    <svg width="11cm" height="6.5cm" viewBox="0 0 1100 650">
      <title>Example feComposite - Examples of feComposite operations</title>
      <desc>Four rows of six pairs of overlapping triangles depicting
            the six different feComposite operators under different
            opacity values and different clearing of the background.</desc>
    	<defs>
        <desc>Define two sets of six filters for each of the six compositing operators.
              The first set wipes out the background image by flooding with opaque white.
              The second set does not wipe out the background, with the result
              that the background sometimes shines through and is other cases
              is blended into itself (i.e., "double-counting").</desc>
        <filter id="overFlood" filterUnits="objectBoundingBox" x="-5%" y="-5%" width="110%" height="110%">
          <feFlood style="flood-color:#ffffff; flood-opacity:1" result="flood"/>
          <feComposite in="SourceGraphic" in2="BackgroundImage" operator="over" result="comp"/>
          <feMerge> <feMergeNode in="flood"/> <feMergeNode in="comp"/> </feMerge>
        </filter>
        <filter id="inFlood" filterUnits="objectBoundingBox" x="-5%" y="-5%" width="110%" height="110%">
          <feFlood style="flood-color:#ffffff; flood-opacity:1" result="flood"/>
          <feComposite in="SourceGraphic" in2="BackgroundImage" operator="in" result="comp"/>
          <feMerge> <feMergeNode in="flood"/> <feMergeNode in="comp"/> </feMerge>
        </filter>
        <filter id="outFlood" filterUnits="objectBoundingBox" x="-5%" y="-5%" width="110%" height="110%">
          <feFlood style="flood-color:#ffffff; flood-opacity:1" result="flood"/>
          <feComposite in="SourceGraphic" in2="BackgroundImage" operator="out" result="comp"/>
          <feMerge> <feMergeNode in="flood"/> <feMergeNode in="comp"/> </feMerge>
        </filter>
        <filter id="atopFlood" filterUnits="objectBoundingBox" x="-5%" y="-5%" width="110%" height="110%">
          <feFlood style="flood-color:#ffffff; flood-opacity:1" result="flood"/>
          <feComposite in="SourceGraphic" in2="BackgroundImage" operator="atop" result="comp"/>
          <feMerge> <feMergeNode in="flood"/> <feMergeNode in="comp"/> </feMerge>
        </filter>
        <filter id="xorFlood" filterUnits="objectBoundingBox" x="-5%" y="-5%" width="110%" height="110%">
          <feFlood style="flood-color:#ffffff; flood-opacity:1" result="flood"/>
          <feComposite in="SourceGraphic" in2="BackgroundImage" operator="xor" result="comp"/>
          <feMerge> <feMergeNode in="flood"/> <feMergeNode in="comp"/> </feMerge>
        </filter>
        <filter id="arithmeticFlood" filterUnits="objectBoundingBox"
                x="-5%" y="-5%" width="110%" height="110%">
          <feFlood style="flood-color:#ffffff; flood-opacity:1" result="flood"/>
          <feComposite in="SourceGraphic" in2="BackgroundImage" result="comp"
                       operator="arithmetic" k1=".5" k2=".5" k3=".5" k4=".5"/>
          <feMerge> <feMergeNode in="flood"/> <feMergeNode in="comp"/> </feMerge>
        </filter>
        <filter id="overNoFlood" filterUnits="objectBoundingBox" x="-5%" y="-5%" width="110%" height="110%">
          <feComposite in="SourceGraphic" in2="BackgroundImage" operator="over" result="comp"/>
        </filter>
        <filter id="inNoFlood" filterUnits="objectBoundingBox" x="-5%" y="-5%" width="110%" height="110%">
          <feComposite in="SourceGraphic" in2="BackgroundImage" operator="in" result="comp"/>
        </filter>
        <filter id="outNoFlood" filterUnits="objectBoundingBox" x="-5%" y="-5%" width="110%" height="110%">
          <feComposite in="SourceGraphic" in2="BackgroundImage" operator="out" result="comp"/>
        </filter>
        <filter id="atopNoFlood" filterUnits="objectBoundingBox" x="-5%" y="-5%" width="110%" height="110%">
          <feComposite in="SourceGraphic" in2="BackgroundImage" operator="atop" result="comp"/>
        </filter>
        <filter id="xorNoFlood" filterUnits="objectBoundingBox" x="-5%" y="-5%" width="110%" height="110%">
          <feComposite in="SourceGraphic" in2="BackgroundImage" operator="xor" result="comp"/>
        </filter>
        <filter id="arithmeticNoFlood" filterUnits="objectBoundingBox"
                x="-5%" y="-5%" width="110%" height="110%">
          <feComposite in="SourceGraphic" in2="BackgroundImage" result="comp"
                       operator="arithmetic" k1=".5" k2=".5" k3=".5" k4=".5"/>
        </filter>
        <path id="Blue100" d="M 0 0 L 100 0 L 100 100 z" style="fill:#00ffff"/>
        <path id="Red100" d="M 0 0 L 0 100 L 100 0 z" style="fill:#ff00ff"/>
        <path id="Blue50" d="M 0 125 L 100 125 L 100 225 z" style="fill:#00ffff; fill-opacity:.5"/>
        <path id="Red50" d="M 0 125 L 0 225 L 100 125 z" style="fill:#ff00ff; fill-opacity:.5"/>
        <g id="TwoBlueTriangles">
          <use xlink:href="#Blue100"/>
          <use xlink:href="#Blue50"/>
        </g>
        <g id="BlueTriangles">
          <use transform="translate(275,25)" xlink:href="#TwoBlueTriangles"/>
          <use transform="translate(400,25)" xlink:href="#TwoBlueTriangles"/>
          <use transform="translate(525,25)" xlink:href="#TwoBlueTriangles"/>
          <use transform="translate(650,25)" xlink:href="#TwoBlueTriangles"/>
          <use transform="translate(775,25)" xlink:href="#TwoBlueTriangles"/>
          <use transform="translate(900,25)" xlink:href="#TwoBlueTriangles"/>
        </g>
      </defs>

      <rect style="fill:none; stroke:blue" x="1" y="1" width="1098" height="648"/>
      <g style="font-family:Verdana; font-size:40; shape-rendering:crispEdges">
        <desc>Render the examples using the filters that draw on top of
              an opaque white surface, thus obliterating the background.</desc>
        <g style="enable-background:new">
          <text x="15" y="75">opacity 1.0</text>
          <text x="15" y="115" style="font-size:27">(with feFlood)</text>
          <text x="15" y="200">opacity 0.5</text>
          <text x="15" y="240" style="font-size:27">(with feFlood)</text>
          <use xlink:href="#BlueTriangles"/>
          <g transform="translate(275,25)">
            <use  xlink:href="#Red100" style="filter:url(#overFlood)"/>
            <use  xlink:href="#Red50" style="filter:url(#overFlood)"/>
            <text x="5" y="275">over</text>
          </g>
          <g transform="translate(400,25)">
            <use  xlink:href="#Red100" style="filter:url(#inFlood)"/>
            <use  xlink:href="#Red50" style="filter:url(#inFlood)"/>
            <text x="35" y="275">in</text>
          </g>
          <g transform="translate(525,25)">
            <use  xlink:href="#Red100" style="filter:url(#outFlood)"/>
            <use  xlink:href="#Red50" style="filter:url(#outFlood)"/>
            <text x="15" y="275">out</text>
          </g>
          <g transform="translate(650,25)">
            <use  xlink:href="#Red100" style="filter:url(#atopFlood)"/>
            <use  xlink:href="#Red50" style="filter:url(#atopFlood)"/>
            <text x="10" y="275">atop</text>
          </g>
          <g transform="translate(775,25)">
            <use  xlink:href="#Red100" style="filter:url(#xorFlood)"/>
            <use  xlink:href="#Red50" style="filter:url(#xorFlood)"/>
            <text x="15" y="275">xor</text>
          </g>
          <g transform="translate(900,25)">
            <use  xlink:href="#Red100" style="filter:url(#arithmeticFlood)"/>
            <use  xlink:href="#Red50" style="filter:url(#arithmeticFlood)"/>
            <text x="-25" y="275">arithmetic</text>
          </g>
        </g>
        <g transform="translate(0,325)" style="enable-background:new">
        <desc>Render the examples using the filters that do not obliterate
              the background, thus sometimes causing the background to continue
              to appear in some cases, and in other cases the background
              image blends into itself ("double-counting").</desc>
          <text x="15" y="75">opacity 1.0</text>
          <text x="15" y="115" style="font-size:27">(without feFlood)</text>
          <text x="15" y="200">opacity 0.5</text>
          <text x="15" y="240" style="font-size:27">(without feFlood)</text>
          <use xlink:href="#BlueTriangles"/>
          <g transform="translate(275,25)">
            <use  xlink:href="#Red100" style="filter:url(#overNoFlood)"/>
            <use  xlink:href="#Red50" style="filter:url(#overNoFlood)"/>
            <text x="5" y="275">over</text>
          </g>
          <g transform="translate(400,25)">
            <use  xlink:href="#Red100" style="filter:url(#inNoFlood)"/>
            <use  xlink:href="#Red50" style="filter:url(#inNoFlood)"/>
            <text x="35" y="275">in</text>
          </g>
          <g transform="translate(525,25)">
            <use  xlink:href="#Red100" style="filter:url(#outNoFlood)"/>
            <use  xlink:href="#Red50" style="filter:url(#outNoFlood)"/>
            <text x="15" y="275">out</text>
          </g>
          <g transform="translate(650,25)">
            <use  xlink:href="#Red100" style="filter:url(#atopNoFlood)"/>
            <use  xlink:href="#Red50" style="filter:url(#atopNoFlood)"/>
            <text x="10" y="275">atop</text>
          </g>
          <g transform="translate(775,25)">
            <use  xlink:href="#Red100" style="filter:url(#xorNoFlood)"/>
            <use  xlink:href="#Red50" style="filter:url(#xorNoFlood)"/>
            <text x="15" y="275">xor</text>
          </g>
          <g transform="translate(900,25)">
            <use  xlink:href="#Red100" style="filter:url(#arithmeticNoFlood)"/>
            <use  xlink:href="#Red50" style="filter:url(#arithmeticNoFlood)"/>
            <text x="-25" y="275">arithmetic</text>
          </g>
        </g>
      </g>
    </svg>

Example feComposite

View this example as SVG (SVG-enabled browsers only)

## 15.13 Filter primitive 'feConvolveMatrix'

feConvolveMatrix applies a matrix convolution filter effect. A convolution combines pixels in the input image with neighboring pixels to produce a resulting image. A wide variety of imaging operations can be achieved through convolutions, including blurring, edge detection, sharpening, embossing and beveling.

A matrix convolution is based on an n-by-m matrix (the convolution kernel) which describes how a given pixel value in the input image is combined with its neighboring pixel values to produce a resulting pixel value. Each result pixel is determined by applying the kernel matrix to the corresponding source pixel and its neighboring pixels.

To illustrate, suppose you have a input image which is 5 pixels by 5 pixels, whose color values are as follows:

        0  20  40 235 235
      100 120 140 235 235
      200 220 240 235 235
      225 225 255 255 255
      225 225 255 255 255

and you define a 3-by-3 convolution kernel as follows:

      1 2 3
      4 5 6
      7 8 9

Let's focus on the pixel at the second row and second column of the image (source pixel value is 120). Assuming the simplest case (where the input image's pixel grid aligns perfectly with the kernel's pixel grid) and assuming default values for attributes divisor, targetX and targetY, then resulting pixel value will be:

    (1*  0 + 2* 20 + 3* 40 +
    4*100 + 5*120 + 6*140 +
    7*200 + 8*220 + 9*240) / (1+2+3+4+5+6+7+8+9)

Because they operate on pixels, matrix convolutions are inherently resolution-dependent. To make 'feConvolveMatrix produce resolution-independent results, an explicit value should be provided for either the filterRes attribute on the 'filter' element and/or attribute kernelUnitLength.

kernelUnitLength, in combination with the other attributes, defines an implicit pixel grid in the filter effects coordinate system (i.e., the coordinate system established by the filterUnits attribute). If the pixel grid established by kernelUnitLength does not align perfectly with the pixel grid established by attribute filterRes, then the input image will be temporarily resampled to align its pixels with kernelUnitLength. The convolution happens on the resampled image. After applying the convolution, the image is resampled back to its original resolution.

    <!ELEMENT feConvolveMatrix (animate|set)* >
    <!ATTLIST feConvolveMatrix
      %filter_primitive_attributes_with_in;
      order CDATA #REQUIRED
      kernelMatrix CDATA #REQUIRED
      divisor %Number; #IMPLIED
      bias %Number; #IMPLIED
      targetX %Integer; #IMPLIED
      targetY %Integer; #IMPLIED
      edgeMode (duplicate|wrap|none) "duplicate"
      kernelUnitLength CDATA #IMPLIED
      preserveAlpha %Boolean; #IMPLIED >

Attribute definitions:

order = "<orderX> [<orderY>]"
  Indicates the number of cells in each dimension for kernelMatrix. The values provided must be <integer>s greater than zero. If two values are provided, the values are separated by space characters and/or a comma. <orderX> indicates the number of columns in the matrix. <orderY> indicates the number of rows in the matrix. If <orderY> is not provided, it defaults to <orderX>.
  A typical value is order="3". It is recommended that only small values (e.g., 3) be used; higher values may result in very high CPU overhead and usually do not produce results that justify the impact on performance.
  If the attribute is not specified, the effect is as if a value of "3" were specified.
  Animatable: yes.
kernelMatrix = "<list of numbers>"
  The list of <number>s that make up the kernel matrix for the convolution. Values are separated by space characters and/or a comma. The number of entries in the list must equal <orderX> times <orderY>.
  Animatable: yes.
divisor = "<number>"
  After applying the kernelMatrix to the input image to yield a number, that number is divided by divisor to yield the final destination color value. A divisor that is the sum of all the matrix values tends to have an evening effect on the overall color intensity of the result. It is an error to specify a divisor of zero. The default value is the sum of all values in kernelMatrix, with the exception that if the sum is zero, then the divisor is set to 1.
  Animatable: yes.
bias = "<number>"
  After applying the kernelMatrix to the input image to yield a number and applying the divisor, the bias attribute is added to each component. One application of bias is when it is desirable to have .5 gray value be the zero response of the filter. If bias is not specified, then the effect is as if a value of zero were specified.
  Animatable: yes.
targetX = "<integer>"
  Determines the positioning in X of the convolution matrix relative to a given target pixel in the input image. The leftmost column of the matrix is column number zero. The value must be such that: 0 <= targetX < orderX. By default, the convolution matrix is centered in X over each pixel of the input image (i.e., targetX = floor ( orderX / 2 )).
  Animatable: yes.
targetY = "<integer>"
  Determines the positioning in Y of the convolution matrix relative to a given target pixel in the input image. The topmost row of the matrix is row number zero. The value must be such that: 0 <= targetY < orderY. By default, the convolution matrix is centered in Y over each pixel of the input image (i.e., targetY = floor ( orderY / 2 )).
  Animatable: yes.
edgeMode = "duplicate | wrap | none"

  Determines how to extend the input image as necessary with color values so that the matrix operations can be applied when the kernel is positioned at or near the edge of the input image.

  "duplicate" indicates that the input image is extended along each of its borders as necessary by duplicating the color values at the given edge of the input image.

      Original N-by-M image, where m=M-1 and n=N-1:
                11 12 ... 1m 1M
                21 22 ... 2m 2M
                .. .. ... .. ..
                n1 n2 ... nm nM
                N1 N2 ... Nm NM

      Extended by two pixels using "duplicate":
        11 11   11 12 ... 1m 1M   1M 1M
        11 11   11 12 ... 1m 1M   1M 1M

        11 11   11 12 ... 1m 1M   1M 1M
        21 21   21 22 ... 2m 2M   2M 2M
        .. ..   .. .. ... .. ..   .. ..
        n1 n1   n1 n2 ... nm nM   nM nM
        N1 N1   N1 N2 ... Nm NM   NM NM

        N1 N1   N1 N2 ... Nm NM   NM NM
        N1 N1   N1 N2 ... Nm NM   NM NM

  "wrap" indicates that the input image is extended by taking the color values from the opposite edge of the image.

      Extended by two pixels using "wrap":
        nm nM   n1 n2 ... nm Nm   n1 n2
        Nm NM   N1 N2 ... Nm NM   N1 N2

        1M 1m   11 12 ... 1m 1M   11 12
        2M 2m   21 22 ... 2m 2M   21 22
        .. ..   .. .. ... .. ..   .. ..
        nm nM   n1 n2 ... nm nM   n1 n2
        Nm NM   N1 N2 ... Nm NM   N1 N2

        1m 1M   11 12 ... 1m 1M   11 12
        2m 2M   21 22 ... 2m 2M   21 22

  "none" indicates that the input image is extended with pixel values of zero for R, G, B and A.

  Animatable: yes.

kernelUnitLength = "<xLength> [<yLength>]"
  Indicates the intended distance in current filter units (i.e., units as determined by the value of attribute filterUnits) between successive columns and rows, respectively, in the kernelMatrix. By specifying value(s) for kernelUnitLength, the kernel becomes defined in a scalable, abstract coordinate system. If kernelUnitLength is not specified, the default value is one pixel in the offscreen bitmap, which is a pixel-based coordinate system, and thus potentially not scalable. For some level of consistency across display media and user agents, it is necessary that a value be provided for at least one of filterRes and kernelUnitLength. In some implementations, the most consistent results and the fastest performance will be achieved if the pixel grid of the temporary offscreen images aligns with the pixel grid of the kernel.
  A negative or zero value is an error (see Error processing).
  Animatable: yes.
preserveAlpha = "false | true"
  A value of false indicates that the convolution will apply to all channels, including the alpha channel.
  A value of true indicates that the convolution will only apply to the color channels. In this case, the filter will temporarily unpremultiply the color component values, apply the kernel, and then re-premultiply at the end.
  If preserveAlpha is not specified, then the effect is as if a value of false were specified.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;, %filter_primitive_attributes_with_in;.

## 15.14 Filter primitive 'feDiffuseLighting'

This filter primitive lights an image using the alpha channel as a bump map. The resulting image is an RGBA opaque image based on the light color with alpha = 1.0 everywhere. The lighting calculation follows the standard diffuse component of the Phong lighting model. The resulting image depends on the light color, light position and surface geometry of the input bump map.

The light map produced by this filter primitive can be combined with a texture image using the multiply term of the arithmetic 'feComposite' compositing method. Multiple light sources can be simulated by adding several of these light maps together before applying it to the texture image.

The resulting RGBA image is computed as follows:

Dr = kd * N.L * Lr
Dg = kd * N.L * Lg
Db = kd * N.L * Lb
Da = 1.0

where

  kd = diffuse lighting constant
  N = surface normal unit vector, a function of x and y
  L = unit vector pointing from surface to light, a function of x and y in the point and spot light cases
  Lr,Lg,Lb = RGB components of light, a function of x and y in the spot light case

N is a function of x and y and depends on the surface gradient as follows:

The surface described by the input alpha image Ain (x,y) is:

Z (x,y) = surfaceScale * Ain (x,y)

Surface normal is calculated using the Sobel gradient 3x3 filter:

Nx (x,y)= - surfaceScale * 1/4*(( I(x+1,y-1) + 2*I(x+1,y) + I(x+1,y+1))
- (I(x-1,y-1) + 2*I(x-1,y) + I(x-1,y+1)))
Ny (x,y)= - surfaceScale * 1/4*(( I(x-1,y+1) + 2*I(x,y+1) + I(x+1,y+1))
- (I(x-1,y-1) + 2*I(x,y-1) + I(x+1,y-1)))
Nz (x,y) = 1.0
N = (Nx, Ny, Nz) / Norm((Nx,Ny,Nz))

L, the unit vector from the image sample to the light, is calculated as follows:

For Infinite light sources it is constant:

Lx = cos(azimuth)*cos(elevation)
Ly = sin(azimuth)*cos(elevation)
Lz = sin(elevation)

For Point and spot lights it is a function of position:

Lx = Lightx - x
Ly = Lighty - y
Lz = Lightz - Z(x,y)
L = (Lx, Ly, Lz) / Norm(Lx, Ly, Lz)

where Lightx, Lighty, and Lightz are the input light position.

Lr,Lg,Lb, the light color vector, is a function of position in the spot light case only:

Lr = Lightr*pow((-L.S),specularExponent)
Lg = Lightg*pow((-L.S),specularExponent)
Lb = Lightb*pow((-L.S),specularExponent)

where S is the unit vector pointing from the light to the point (pointsAtX, pointsAtY, pointsAtZ) in the x-y plane:

Sx = pointsAtX - Lightx
Sy = pointsAtY - Lighty
Sz = pointsAtZ - Lightz
S = (Sx, Sy, Sz) / Norm(Sx, Sy, Sz)

If L.S is positive, no light is present. (Lr = Lg = Lb = 0)

    <!ELEMENT feDiffuseLighting ((feDistantLight|fePointLight|feSpotLight),(animate|set|animateColor)*) >
    <!ATTLIST feDiffuseLighting
      %stdAttrs;
      class %ClassList; #IMPLIED
      style %StyleSheet; #IMPLIED
      %PresentationAttributes-LightingEffects;
      %filter_primitive_attributes_with_in;
      surfaceScale %Number; #IMPLIED
      diffuseConstant %Number; #IMPLIED >

Attribute definitions:

surfaceScale = "<number>"
  height of surface when Ain = 1.
  If the attribute is not specified, then the effect is as if a value of 1 were specified.
  Animatable: yes.
diffuseConstant = "<number>"
  kd in Phong lighting model. In SVG, this can be any non-negative number.
  If the attribute is not specified, then the effect is as if a value of 1 were specified.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;, %filter_primitive_attributes_with_in;.

The light source is defined by one of the child elements 'feDistantLight', 'fePointLight' or 'feSpotLight'. The light color is specified by property 'lighting-color'.

## 15.15 Filter primitive 'feDisplacementMap'

This filter primitive uses the pixels values from the image from in2 to spatially displace the image from in. This is the transformation to be performed:

    P'(x,y) <- P( x + scale * ((XC(x,y) - .5), y + scale * (YC(x,y) - .5))

where P(x,y) is the input image, in, and P'(x,y) is the destination. XC(x,y) and YC(x,y) are the component values of the designated by the xChannelSelector and yChannelSelector. For example, to use the R component of in2 to control displacement in x and the G component of Image2 to control displacement in y, set xChannelSelector to "R" and yChannelSelector to "G".

The displacement map defines the inverse of the mapping performed.

This filter can have arbitrary non-localized effect on the input which might require substantial buffering in the processing pipeline. However with this formulation, any intermediate buffering needs can be determined by scale which represents the maximum displacement in either x or y.

    <!ELEMENT feDisplacementMap (animate|set)* >
    <!ATTLIST feDisplacementMap
      %stdAttrs;
      %filter_primitive_attributes_with_in;
      in2 CDATA #REQUIRED
      scale %Number; #IMPLIED
      xChannelSelector (R | G | B | A) "A"
      yChannelSelector (R | G | B | A) "A" >

Attribute definitions:

scale = "<number>"
  Displacement scale factor.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.
xChannelSelector = "R | G | B | A"
  Indicates which channel from in2 to use to displace the pixels in in along the x-axis.
  Animatable: yes.
yChannelSelector = "R | G | B | A"
  Indicates which channel from in2 to use to displace the pixels in in along the y-axis.
  Animatable: yes.
in2 = "(see in attribute)"
  The second input image, which is used to displace the pixels in the image from attribute in. This attribute can take on the same values as the in attribute.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;, %filter_primitive_attributes_with_in;.

## 15.16 Filter primitive 'feFlood'

This filter primitive creates a rectangle filled with the color and opacity values from properties 'flood-color' and 'flood-opacity'. The rectangle is as large as the filter primitive subregion established by the x, y, width and height attributes on the 'feFlood' element.

    <!ELEMENT feFlood (animate|set|animateColor)* >
    <!ATTLIST feFlood
      %stdAttrs;
      class %ClassList; #IMPLIED
      style %StyleSheet; #IMPLIED
      %PresentationAttributes-feFlood;
      %filter_primitive_attributes_with_in; >

Attributes defined elsewhere:
  %stdAttrs;, %filter_primitive_attributes_with_in;, class, style, %PresentationAttributes-feFlood;.

The 'flood-color' property indicates what color to use to flood the current filter primitive subregion. The keyword currentColor and ICC colors can be specified in the same manner as within a <paint> specification for the 'fill' and 'stroke' properties.

'flood-color'

  Value: | currentColor | <color> [icc-color(<name>[,<icccolorvalue>]*)] | inherit
  Initial: | black
  Applies to: | 'feFlood' elements
  Inherited: | no
  Percentages: | N/A
  Media: | visual
  Animatable: | yes

The 'flood-opacity' property defines the opacity value to use across the entire filter primitive subregion.

'flood-opacity'

  Value: | <alphavalue> | inherit
  Initial: | 1
  Applies to: | 'feFlood' elements
  Inherited: | no
  Percentages: | N/A
  Media: | visual
  Animatable: | yes

## 15.17 Filter primitive 'feGaussianBlur'

This filter primitive performs a Gaussian blur on the input image.

The Gaussian blur kernel is an approximation of the normalized convolution:

H(x) = exp(-x2/ (2s2)) / sqrt(2* pi*s2)

where 's' is the standard deviation specified by stdDeviation.

The value of stdDeviation can be either one or two numbers. If two numbers are provided, the first number represents a standard deviation value along the x-axis of the current coordinate system and the second value represents a standard deviation in Y. If one number is provided, then that value is used for both X and Y.

Even if only one value is provided for stdDeviation, this can be implemented as a separable convolution.

For larger values of 's' (s >= 2.0), an approximation can be used: Three successive box-blurs build a piece-wise quadratic convolution kernel, which approximates the Gaussian kernel to within roughly 3%.

let d = floor(s * 3*sqrt(2*pi)/4 + 0.5)

... if d is odd, use three box-blurs of size 'd', centered on the output pixel.

... if d is even, two box-blurs of size 'd' (the first one centered one pixel to the left, the second one centered one pixel to the right of the output pixel) and one box blur of size 'd+1' centered on the output pixel.

Frequently this operation will take place on alpha-only images, such as that produced by the built-in input, SourceAlpha. The implementation may notice this and optimize the single channel case. If the input has infinite extent and is constant, this operation has no effect. If the input has infinite extent and is a tile, the filter is evaluated with periodic boundary conditions.

    <!ELEMENT feGaussianBlur (animate|set)* >
    <!ATTLIST feGaussianBlur
      %stdAttrs;
      %filter_primitive_attributes_with_in;
      stdDeviation CDATA #IMPLIED >

Attribute definitions:

stdDeviation = "<number> [<number>]"
  The standard deviation for the blur operation. If two <number>s are provided, the first number represents a standard deviation value along the x-axis of the current coordinate system and the second value represents a standard deviation in Y. If one number is provided, then that value is used for both X and Y.
  A negative value is an error (see Error processing). A value of zero disables the effect of the given filter primitive (i.e., the result is a fully transparent image).
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;, %filter_primitive_attributes_with_in;.

The example at the start of this chapter makes use of the feGaussianBlur filter primitive to create a drop shadow effect.

## 15.18 Filter primitive 'feImage'

This filter primitive refers to a graphic external to this filter element, which is loaded or rendered into an RGBA raster and becomes the result of the filter primitive.

This filter primitive can refer to an external image or can be a reference to another piece of SVG. It produces an image similar to the built-in image source SourceGraphic except that the graphic comes from an external source.

If the xlink:href references a stand-alone image resource such as a JPEG or PNG file, then the image resource is rendered according to the behavior of the 'image' element; otherwise, the referenced resource is rendered according to the behavior of the 'use' element. In either case, the current user coordinate system depends on the value of attribute primitiveUnits on the 'filter' element.

    <!ELEMENT feImage (animate|set|animateTransform)* >
    <!ATTLIST feImage
      %stdAttrs;
      %xlinkRefAttrs;
      xlink:href %URI; #REQUIRED
      %langSpaceAttrs;
      externalResourcesRequired %Boolean; #IMPLIED
      class %ClassList; #IMPLIED
      style %StyleSheet; #IMPLIED
      %PresentationAttributes-All;
      transform %TransformList; #IMPLIED
      %filter_primitive_attributes; >

Attributes defined elsewhere:
  %stdAttrs;, %langSpaceAttrs;, class, transform, externalResourcesRequired, %xlinkRefAttrs;, xlink:href, style, %PresentationAttributes-All;, %filter_primitive_attributes;.

## 15.19 Filter primitive 'feMerge'

This filter primitive composites input image layers on top of each other using the over operator with Input1 on the bottom and the last specified input, InputN, on top.

Many effects produce a number of intermediate layers in order to create the final output image. This filter allows us to collapse those into a single image. Although this could be done by using n-1 Composite-filters, it is more convenient to have this common operation available in this form, and offers the implementation some additional flexibility.

Each 'feMerge' element can have any number of 'feMergeNode' subelements, each of which has an in attribute.

The canonical implementation of feMerge is to render the entire effect into one RGBA layer, and then render the resulting layer on the output device. In certain cases (in particular if the output device itself is a continuous tone device), and since merging is associative, it might be a sufficient approximation to evaluate the effect one layer at a time and render each layer individually onto the output device bottom to top.

If the topmost image input is SourceGraphic, the implementation is encouraged to render the layers up to that point, and then render the SourceGraphic directly from its vector description on top.

    <!ELEMENT feMerge (feMergeNode)* >
    <!ATTLIST feMerge
      %stdAttrs;
      %filter_primitive_attributes; >

    <!ELEMENT feMergeNode (animate|set)* >
    <!ATTLIST feMergeNode
      %stdAttrs;
      in CDATA #IMPLIED >

Attributes defined elsewhere:
  %stdAttrs;, %filter_primitive_attributes;, in.

The example at the start of this chapter makes use of the feMerge filter primitive to composite two intermediate filter results together.

## 15.20 Filter primitive 'feMorphology'

This filter primitive performs "fattening" or "thinning" of artwork. It is particularly useful for fattening or thinning an alpha channel.

The dilation (or erosion) kernel is a rectangle with a width of 2*x-radius+1 and a height of 2*y-radius+1. In dilation, the output pixel is the individual component-wise maximum of the corresponding R,G,B,A values in the input image's kernel rectangle. In erosion, the output pixel is the individual component-wise minimum of the corresponding R,G,B,A values in the input image's kernel rectangle.

Frequently this operation will take place on alpha-only images, such as that produced by the built-in input, SourceAlpha. In that case, the implementation might want to optimize the single channel case.

If the input has infinite extent and is constant, this operation has no effect. If the input has infinite extent and is a tile, the filter is evaluated with periodic boundary conditions.

    <!ELEMENT feMorphology (animate|set)* >
    <!ATTLIST feMorphology
      %stdAttrs;
      %filter_primitive_attributes_with_in;
      operator (erode | dilate) "erode"
      radius %Length; #IMPLIED >

Attribute definitions:

operator = "erode | dilate"
  A keyword indicating whether to erode (i.e., thin) or dilate (fatten) the source graphic.
  Animatable: yes.
radius = "<number> [<number>]"
  The radius (or radii) for the operation. If two <number>s are provided, the first number represents a x-radius in the current coordinate system and the second value represents a y-radius. If one number is provided, then that value is used for both X and Y.
  A negative value is an error (see Error processing). A value of zero disables the effect of the given filter primitive (i.e., the result is a fully transparent image).
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;, %filter_primitive_attributes_with_in;.

Example feMorphology shows examples of the four types of feMorphology operations.

    <?xml version="1.0"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20001102//EN"
              "http://www.w3.org/TR/2000/CR-SVG-20001102/DTD/svg-20001102.dtd">
    <svg width="5cm" height="7cm" viewBox="0 0 700 500">
      <title>Example feMorphology - Examples of erode and dilate</title>
      <desc>Five text strings drawn as outlines.
            The first is unfiltered. The second and third use 'erode'.
            The fourth and fifth use 'dilate'.</desc>
      <defs>
        <filter id="Erode3">
          <feMorphology operator="erode" in="SourceGraphic" radius="3" />
        </filter>
        <filter id="Erode6">
          <feMorphology operator="erode" in="SourceGraphic" radius="6" />
        </filter>
        <filter id="Dilate3">
          <feMorphology operator="dilate" in="SourceGraphic" radius="3" />
        </filter>
        <filter id="Dilate6">
          <feMorphology operator="dilate" in="SourceGraphic" radius="6" />
        </filter>
      </defs>
      <rect style="fill:none; stroke:blue; stroke-width:2"
            x="1" y="1" width="698" height="498"/>
      <g style="enable-background: new">
        <g style="font-family:Verdana; font-size:75;
                  fill:none; stroke:black; stroke-width:6">
          <text x="50" y="90">Unfiltered</text>
          <text x="50" y="180" style="filter:url(#Erode3)">Erode radius 3</text>
          <text x="50" y="270" style="filter:url(#Erode6)">Erode radius 6</text>
          <text x="50" y="360" style="filter:url(#Dilate3)">Dilate radius 3</text>
          <text x="50" y="450" style="filter:url(#Dilate6)">Dilate radius 6</text>
        </g>
      </g>
    </svg>

Example feMorphology

View this example as SVG (SVG-enabled browsers only)

## 15.21 Filter primitive 'feOffset'

This filter primitive offsets the input image relative to its current position in the image space by the specified vector.

This is important for effects like drop shadows.

    <!ELEMENT feOffset (animate|set)* >
    <!ATTLIST feOffset
      %stdAttrs;
      %filter_primitive_attributes_with_in;
      dx %Length; #IMPLIED
      dy %Length; #IMPLIED >

Attribute definitions:

dx = "<length>"
  The amount to offset the input graphic along the x-axis.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.
dy = "<length>"
  The amount to offset the input graphic along the y-axis.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;, %filter_primitive_attributes_with_in;.

The example at the start of this chapter makes use of the feOffset filter primitive to offset the drop shadow from the original source graphic.

## 15.22 Filter primitive 'feSpecularLighting'

This filter primitive lights a source graphic using the alpha channel as a bump map. The resulting image is an RGBA image based on the light color. The lighting calculation follows the standard specular component of the Phong lighting model. The resulting image depends on the light color, light position and surface geometry of the input bump map. The result of the lighting calculation is added. The filter primitive assumes that the viewer is at infinity in the z direction (i.e., the unit vector in the eye direction is (0,0,1) everywhere).

This filter primitive produces an image which contains the specular reflection part of the lighting calculation. Such a map is intended to be combined with a texture using the add term of the arithmetic 'feComposite' method. Multiple light sources can be simulated by adding several of these light maps before applying it to the texture image.

The resulting RGBA image is computed as follows:

Sr = ks * pow(N.H, specularExponent) * Lr
Sg = ks * pow(N.H, specularExponent) * Lg
Sb = ks * pow(N.H, specularExponent) * Lb
Sa = max(Sr, Sg, Sb)

where

  ks = specular lighting constant
  N = surface normal unit vector, a function of x and y
  H = "halfway" unit vectorbetween eye unit vector and light unit vector
  Lr,Lg,Lb = RGB components of light

See 'feDiffuseLighting' for definition of N and (Lr, Lg, Lb).

The definition of H reflects our assumption of the constant eye vector E = (0,0,1):

H = (L + E) / Norm(L+E)

where L is the light unit vector.

Unlike the 'feDiffuseLighting', the 'feSpecularLighting' filter produces a non-opaque image. This is due to the fact that the specular result (Sr,Sg,Sb,Sa) is meant to be added to the textured image. The alpha channel of the result is the max of the color components, so that where the specular light is zero, no additional coverage is added to the image and a fully white highlight will add opacity.

The 'feDiffuseLighting' and 'feSpecularLighting' filters will often be applied together. An implementation may detect this and calculate both maps in one pass, instead of two.

    <!ELEMENT feSpecularLighting ((feDistantLight|fePointLight|feSpotLight),(animate|set|animateColor)*) >
    <!ATTLIST feSpecularLighting
      %stdAttrs;
      class %ClassList; #IMPLIED
      style %StyleSheet; #IMPLIED
      %PresentationAttributes-LightingEffects;
      %filter_primitive_attributes_with_in;
      surfaceScale %Number; #IMPLIED
      specularConstant %Number; #IMPLIED
      specularExponent %Number; #IMPLIED >

Attribute definitions:

surfaceScale = "<number>"
  height of surface when Ain = 1.
  If the attribute is not specified, then the effect is as if a value of 1 were specified.
  Animatable: yes.
specularConstant = "<number>"
  ks in Phong lighting model. In SVG, this can be any non-negative number.
  If the attribute is not specified, then the effect is as if a value of 1 were specified.
  Animatable: yes.
specularExponent = "<number>"
  Exponent for specular term, larger is more "shiny". Range 1.0 to 128.0.
  If the attribute is not specified, then the effect is as if a value of 1 were specified.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;, %filter_primitive_attributes_with_in;.

The light source is defined by one of the child elements 'feDistantLight', 'fePointLight' or 'feDistantLight'. The light color is specified by property 'lighting-color'.

The example at the start of this chapter makes use of the feSpecularLighting filter primitive to achieve a highly reflective, 3D glowing effect.

## 15.23 Filter primitive 'feTile'

This filter primitive fills a target rectangle with a repeated, tiled pattern of an input image. The target rectangle is as large as the filter primitive subregion established by the x, y, width and height attributes on the 'feTile' element.

Typically, the input image has been defined with its own filter primitive subregion in order to define a reference tile. 'feTile' replicates the reference tile in both X and Y to completely fill the target rectangle. The top/left corner of each given tile is at location `(x+i*width,y+j*height)`, where `(x,y)` represents the top/left of the input image's filter primitive subregion, `width` and `height` represent the width and height of the input image's filter primitive subregion, and `i` and `j` can be any integer value. In most cases, the input image will have a smaller filter primitive subregion than the 'feTile' in order to achieve a repeated pattern effect.

    <!ELEMENT feTile (animate|set)* >
    <!ATTLIST feTile
      %stdAttrs;
      %filter_primitive_attributes_with_in; >

Attributes defined elsewhere:
  %stdAttrs;, %filter_primitive_attributes_with_in;.

## 15.24 Filter primitive 'feTurbulence'

This filter primitive creates an image using the Perlin turbulence function. It allows the synthesis of artificial textures like clouds or marble. For a detailed description the of the Perlin turbulence function, see "Texturing and Modeling", Ebert et al, AP Professional, 1994. The resulting image will have maximal size in image space.

It is possible to create bandwidth-limited noise by synthesizing only one octave.

The following C code shows the exact algorithm used for this filter effect.
For fractalSum, you get a turbFunctionResult that is aimed at a range of -1 to 1 (the actual result might exceed this range in some cases). To convert to a color value, use the formula `colorValue = ((turbFunctionResult * 255) + 255) / 2`, then clamp to the range 0 to 255.
For turbulence, you get a turbFunctionResult that is aimed at a range of 0 to 1 (the actual result might exceed this range in some cases). To convert to a color value, use the formula `colorValue = (turbFunctionResult * 255)`, then clamp to the range 0 to 255.
The following order is used for applying the pseudo random numbers. An initial seed value is computed based on attribute seed. Then the implementation computes the lattice points for R, then continues getting additional pseudo random numbers relative to the last generated pseudo random number and computes the lattice points for G, and so on for B and A.

    /* Produces results in the range [1, 2**31 - 2].
    Algorithm is: r = (a * r) mod m
    where a = 16807 and m = 2**31 - 1 = 2147483647
    See [Park & Miller], CACM vol. 31 no. 10 p. 1195, Oct. 1988
    To test: the algorithm should produce the result 1043618065
    as the 10,000th generated number if the original seed is 1.
    */
    #define RAND_m 2147483647 /* 2**31 - 1 */
    #define RAND_a 16807 /* 7**5; primitive root of m */
    #define RAND_q 127773 /* m / a */
    #define RAND_r 2836 /* m % a */

    long setup_seed(long lSeed)
    {
      if (lSeed <= 0) lSeed = -(lSeed % (RAND_m - 1)) + 1;
      if (lSeed > RAND_m - 1) lSeed = RAND_m - 1;
      return lSeed;
    }

    long random(long lSeed)
    {
      long result;
      result = RAND_a * (lSeed % RAND_q) - RAND_r * (lSeed / RAND_q);
      if (result <= 0) result += RAND_m;
      return result;
    }

    #define BSize 0x100
    #define BM 0xff
    #define PerlinN 0x1000
    #define NP 12 /* 2^PerlinN */
    #define NM 0xfff
    static uLatticeSelector[BSize + BSize + 2];
    static double fGradient[4][BSize + BSize + 2][2];
    struct StitchInfo
    {
      int nWidth; // How much to subtract to wrap for stitching.
      int nHeight;
      int nWrapX; // Minimum value to wrap.
      int nWrapY;
    };

    static void init(long lSeed)
    {
      double s;
      int i, j, k;
      lSeed = setup_seed(lSeed);
      for(k = 0; k < 4; k++)
      {
        for(i = 0; i < BSize; i++)
        {
          uLatticeSelector[i] = i;
          for (j = 0; j < 2; j++)
            fGradient[k][i][j] = (double)(((lSeed = random(lSeed)) % (BSize + BSize)) - BSize) / BSize;
          s = double(sqrt(fGradient[k][i][0] * fGradient[k][i][0] + fGradient[k][i][1] * fGradient[k][i][1]));
          fGradient[k][i][0] /= s;
          fGradient[k][i][1] /= s;
        }
      }
      while(--i)
      {
        k = uLatticeSelector[i];
        uLatticeSelector[i] = uLatticeSelector[j = (lSeed = random(lSeed)) % BSize];
        uLatticeSelector[j] = k;
      }
      for(i = 0; i < BSize + 2; i++)
      {
        uLatticeSelector[BSize + i] = uLatticeSelector[i];
        for(k = 0; k < 4; k++)
          for(j = 0; j < 2; j++)
            fGradient[k][BSize + i][j] = fGradient[k][i][j];
      }
    }

    #define s_curve(t) ( t * t * (3. - 2. * t) )
    #define lerp(t, a, b) ( a + t * (b - a) )
    double noise2(int nColorChannel, double vec[2], StitchInfo *pStitchInfo)
    {
      int bx0, bx1, by0, by1, b00, b10, b01, b11;
      double rx0, rx1, ry0, ry1, *q, sx, sy, a, b, t, u, v;
      register i, j;
      t = vec[0] + PerlinN;
      bx0 = (int)t;
      bx1 = bx0+1;
      rx0 = t - (int)t;
      rx1 = rx0 - 1.0f;
      t = vec[1] + PerlinN;
      by0 = (int)t;
      by1 = by0+1;
      ry0 = t - (int)t;
      ry1 = ry0 - 1.0f;

      // If stitching, adjust lattice points accordingly.
      if(pStitchInfo != NULL)
      {
        if(bx0 >= pStitchInfo->nWrapX)
          bx0 -= pStitchInfo->nWidth;
        if(bx1 >= pStitchInfo->nWrapX)
          bx1 -= pStitchInfo->nWidth;
        if(by0 >= pStitchInfo->nWrapY)
          by0 -= pStitchInfo->nHeight;
        if(by1 >= pStitchInfo->nWrapY)
          by1 -= pStitchInfo->nHeight;
      }

      bx0 &= BM;
      bx1 &= BM;
      by0 &= BM;
      by1 &= BM;

      i = uLatticeSelector[bx0];
      j = uLatticeSelector[bx1];
      b00 = uLatticeSelector[i + by0];
      b10 = uLatticeSelector[j + by0];
      b01 = uLatticeSelector[i + by1];
      b11 = uLatticeSelector[j + by1];
      sx = double(s_curve(rx0));
      sy = double(s_curve(ry0));
      q = fGradient[nColorChannel][b00]; u = rx0 * q[0] + ry0 * q[1];
      q = fGradient[nColorChannel][b10]; v = rx1 * q[0] + ry0 * q[1];
      a = lerp(sx, u, v);
      q = fGradient[nColorChannel][b01]; u = rx0 * q[0] + ry1 * q[1];
      q = fGradient[nColorChannel][b11]; v = rx1 * q[0] + ry1 * q[1];
      b = lerp(sx, u, v);
      return lerp(sy, a, b);
    }

    double turbulence(int nColorChannel, double *point, double fBaseFreqX, double fBaseFreqY,
              int nNumOctaves, bool bFractalSum, bool bDoStitching,
              double fTileX, double fTileY, double fTileWidth, double fTileHeight)
    {
      StitchInfo stitch;
      StitchInfo *pStitchInfo = NULL; // Not stitching when NULL.

      // Adjust the base frequencies if necessary for stitching.
      if(bDoStitching)
      {
        // When stitching tiled turbulence, the frequencies must be adjusted
        // so that the tile borders will be continuous.
        double fLoFreq = double(floor(fTileWidth * fBaseFreqX)) / fTileWidth;
        double fHiFreq = double(ceil(fTileWidth * fBaseFreqX)) / fTileWidth;
        if(fBaseFreqX / fLoFreq < fHiFreq / fBaseFreqX)
          fBaseFreqX = fLoFreq;
        else
          fBaseFreqX = fHiFreq;

        fLoFreq = double(floor(fTileHeight * fBaseFreqX)) / fTileHeight;
        fHiFreq = double(ceil(fTileHeight * fBaseFreqX)) / fTileHeight;
        if(fBaseFreqY / fLoFreq < fHiFreq / fBaseFreqY)
          fBaseFreqY = fLoFreq;
        else
          fBaseFreqY = fHiFreq;

        // Set up initial stitch values.
        pStitchInfo = &stitch;
        stitch.nWidth = int(fTileWidth * fBaseFreqX + 0.5f);
        stitch.nWrapX = fTileX * fBaseFreqX + PerlinN + stitch.nWidth;
        stitch.nHeight = int(fTileHeight * fBaseFreqY + 0.5f);
        stitch.nWrapY = fTileY * fBaseFreqY + PerlinN + stitch.nHeight;
      }

      double fSum = 0.0f;
      double vec[2];
      vec[0] = point[0] * fBaseFreqX;
      vec[1] = point[1] * fBaseFreqY;
      double ratio = 1;
      for(int nOctave = 0; nOctave < nNumOctaves; nOctave++)
      {
        if(bFractalSum)
          fSum += double(noise2(nColorChannel, vec, pStitchInfo) / ratio);
        else
          fSum += double(fabs(noise2(nColorChannel, vec, pStitchInfo)) / ratio);

        vec[0] *= 2;
        vec[1] *= 2;
        ratio *= 2;

        if(pStitchInfo != NULL)
        {
          // Update stitch values. Subtracting PerlinN before the multiplication and
          // adding it afterward simplifies to subtracting it once.
          stitch.nWidth *= 2;
          stitch.nWrapX = 2 * stitch.nWrapX - PerlinN;
          stitch.nHeight *= 2;
          stitch.nWrapY = 2 * stitch.nWrapY - PerlinN;
        }
      }
      return fSum;
    }

    <!ELEMENT feTurbulence (animate|set)* >
    <!ATTLIST feTurbulence
      %stdAttrs;
      %filter_primitive_attributes;
      baseFrequency CDATA #IMPLIED
      numOctaves %Integer; #IMPLIED
      seed %Number; #IMPLIED
      stitchTiles (stitch | noStitch) "noStitch"
      type (fractalNoise | turbulence) "turbulence" >

Attribute definitions:

baseFrequency = "<number> [<number>]"
  The base frequency (frequencies) parameter(s) for the noise function. If two <number>s are provided, the first number represents a base frequency in the X direction and the second value represents a base frequency in the Y direction. If one number is provided, then that value is used for both X and Y.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.
numOctaves = "<integer>"
  The numOctaves parameter for the noise function.
  If the attribute is not specified, then the effect is as if a value of 1 were specified.
  Animatable: yes.
seed = "<number>"
  The starting number for the pseudo random number generator.
  If the attribute is not specified, then the effect is as if a value of 0 were specified.
  Animatable: yes.
stitchTiles = "stitch | noStitch"
  If stitchTiles="noStitch", no attempt it made to achieve smooth transitions at the border of tiles which contain a turbulence function. Sometimes the result will show clear discontinuities at the tile borders.
  If stitchTiles="stitch", then the user agent will automatically adjust baseFrequency-x and baseFrequency-y values such that the feTurbulence node's width and height (i.e., the width and height of the current subregion) contains an integral number of the Perlin tile width and height for the first octave. The baseFrequency will be adjusted up or down depending on which way has the smallest relative (not absolute) change as follows: Given the frequency, calculate `lowFreq=floor(width*frequency)/width` and `hiFreq=ceil(width*frequency)/width`. If frequency/lowFreq < hiFreq/frequency then use lowFreq, else use hiFreq. While generating turbulence values, generate lattice vectors as normal for Perlin Noise, except for those lattice points that lie on the right or bottom edges of the active area (the size of the resulting tile). In those cases, copy the lattice vector from the opposite edge of the active area.
  Animatable: yes.
type = "fractalNoise | turbulence"
  Indicates whether the filter primitive should perform a noise or turbulence function.
  Animatable: yes.

Attributes defined elsewhere:
  %stdAttrs;, %filter_primitive_attributes;.

Example feTurbulence shows the effects of various parameter settings for feTurbulence.

    <?xml version="1.0"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20001102//EN"
              "http://www.w3.org/TR/2000/CR-SVG-20001102/DTD/svg-20001102.dtd">
    <svg width="450px" height="325px" viewBox="0 0 450 325">
      <title>Example feTurbulence - Examples of feTurbulence operations</title>
      <desc>Six rectangular areas showing the effects of
            various parameter settings for feTurbulence.</desc>
      <g  style="font-family:Verdana; text-anchor:middle; font-size:10">
        <defs>
          <filter id="Turb1" filterUnits="objectBoundingBox"
                  x="0%" y="0%" width="100%" height="100%">
            <feTurbulence type="turbulence" baseFrequency="0.05" numOctaves="2"/>
          </filter>
          <filter id="Turb2" filterUnits="objectBoundingBox"
                  x="0%" y="0%" width="100%" height="100%">
            <feTurbulence type="turbulence" baseFrequency="0.1" numOctaves="2"/>
          </filter>
          <filter id="Turb3" filterUnits="objectBoundingBox"
                  x="0%" y="0%" width="100%" height="100%">
            <feTurbulence type="turbulence" baseFrequency="0.05" numOctaves="8"/>
          </filter>
          <filter id="Turb4" filterUnits="objectBoundingBox"
                  x="0%" y="0%" width="100%" height="100%">
            <feTurbulence type="fractalNoise" baseFrequency="0.1" numOctaves="4"/>
          </filter>
          <filter id="Turb5" filterUnits="objectBoundingBox"
                  x="0%" y="0%" width="100%" height="100%">
            <feTurbulence type="fractalNoise" baseFrequency="0.4" numOctaves="4"/>
          </filter>
          <filter id="Turb6" filterUnits="objectBoundingBox"
                  x="0%" y="0%" width="100%" height="100%">
            <feTurbulence type="fractalNoise" baseFrequency="0.1" numOctaves="1"/>
          </filter>
        </defs>

        <rect x="1" y="1" width="448" height="323"
              style="fill:none; stroke:blue; stroke-width:1" />

        <rect x="25" y="25" width="100" height="75" style="filter:url(#Turb1)" />
        <text x="75" y="117">type=turbulence</text>
        <text x="75" y="129">baseFrequency=0.05</text>
        <text x="75" y="141">numOctaves=2</text>

        <rect x="175" y="25" width="100" height="75" style="filter:url(#Turb2)" />
        <text x="225" y="117">type=turbulence</text>
        <text x="225" y="129">baseFrequency=0.1</text>
        <text x="225" y="141">numOctaves=2</text>

        <rect x="325" y="25" width="100" height="75" style="filter:url(#Turb3)" />
        <text x="375" y="117">type=turbulence</text>
        <text x="375" y="129">baseFrequency=0.05</text>
        <text x="375" y="141">numOctaves=8</text>

        <rect x="25" y="180" width="100" height="75" style="filter:url(#Turb4)" />
        <text x="75" y="272">type=fractalNoise</text>
        <text x="75" y="284">baseFrequency=0.1</text>
        <text x="75" y="296">numOctaves=4</text>

        <rect x="175" y="180" width="100" height="75" style="filter:url(#Turb5)" />
        <text x="225" y="272">type=fractalNoise</text>
        <text x="225" y="284">baseFrequency=0.4</text>
        <text x="225" y="296">numOctaves=4</text>

        <rect x="325" y="180" width="100" height="75" style="filter:url(#Turb6)" />
        <text x="375" y="272">type=fractalNoise</text>
        <text x="375" y="284">baseFrequency=0.1</text>
        <text x="375" y="296">numOctaves=1</text>
      </g>
    </svg>

Example feTurbulence

View this example as SVG (SVG-enabled browsers only)

## 15.25 DOM interfaces

The following interfaces are defined below: SVGFilterElement, SVGFilterPrimitiveStandardAttributes, SVGFEBlendElement, SVGFEColorMatrixElement, SVGFEComponentTransferElement, SVGComponentTransferFunctionElement, SVGFEFuncRElement, SVGFEFuncGElement, SVGFEFuncBElement, SVGFEFuncAElement, SVGFECompositeElement, SVGFEConvolveMatrixElement, SVGFEDiffuseLightingElement, SVGFEDistantLightElement, SVGFEPointLightElement, SVGFESpotLightElement, SVGFEDisplacementMapElement, SVGFEFloodElement, SVGFEGaussianBlurElement, SVGFEImageElement, SVGFEMergeElement, SVGFEMergeNodeElement, SVGFEMorphologyElement, SVGFEOffsetElement, SVGFESpecularLightingElement, SVGFETileElement, SVGFETurbulenceElement.

### Interface SVGFilterElement

The SVGFilterElement interface corresponds to the 'filter' element.

IDL Definition

      interface SVGFilterElement :
                      SVGElement,
                      SVGURIReference,
                      SVGLangSpace,
                      SVGExternalResourcesRequired,
                      SVGStylable,
                      SVGUnitTypes {

        readonly attribute SVGAnimatedEnumeration filterUnits;
        readonly attribute SVGAnimatedEnumeration primitiveUnits;
        readonly attribute SVGAnimatedLength      x;
        readonly attribute SVGAnimatedLength      y;
        readonly attribute SVGAnimatedLength      width;
        readonly attribute SVGAnimatedLength      height;
        readonly attribute SVGAnimatedInteger    filterResX;
        readonly attribute SVGAnimatedInteger    filterResY;

        void setFilterRes ( in unsigned long filterResX, in unsigned long filterResY );
      };

Attributes
  readonly SVGAnimatedEnumeration filterUnits
    Corresponds to attribute filterUnits on the given 'filter' element. Takes one of the constants defined in SVGUnitTypes.
  readonly SVGAnimatedEnumeration primitiveUnits
    Corresponds to attribute primitiveUnits on the given 'filter' element. Takes one of the constants defined in SVGUnitTypes.
  readonly SVGAnimatedLength x
    Corresponds to attribute x on the given 'filter' element.
  readonly SVGAnimatedLength y
    Corresponds to attribute y on the given 'filter' element.
  readonly SVGAnimatedLength width
    Corresponds to attribute width on the given 'filter' element.
  readonly SVGAnimatedLength height
    Corresponds to attribute height on the given 'filter' element.
  readonly SVGAnimatedInteger filterResX
    Corresponds to attribute filterRes on the given 'filter' element. Contains the X component of attribute filterRes.
  readonly SVGAnimatedInteger filterResY
    Corresponds to attribute filterRes on the given 'filter' element. Contains the Y component (possibly computed automatically) of attribute filterRes.
Methods
  setFilterRes
    Sets the values for attribute filterRes.
    Parameters

      in unsigned long filterResX |  | The X component of attribute filterRes.
      in unsigned long filterResY |  | The Y component of attribute filterRes.

    No Return Value
    No Exceptions

### Interface SVGFilterPrimitiveStandardAttributes

This interface defines the set of DOM attributes that are common across the filter interfaces.

IDL Definition

      interface SVGFilterPrimitiveStandardAttributes {

        readonly attribute SVGAnimatedLength x;
        readonly attribute SVGAnimatedLength y;
        readonly attribute SVGAnimatedLength width;
        readonly attribute SVGAnimatedLength height;
        readonly attribute SVGAnimatedString result;
      };

Attributes
  readonly SVGAnimatedLength x
    Corresponds to attribute x on the given element.
  readonly SVGAnimatedLength y
    Corresponds to attribute y on the given element.
  readonly SVGAnimatedLength width
    Corresponds to attribute width on the given element.
  readonly SVGAnimatedLength height
    Corresponds to attribute height on the given element.
  readonly SVGAnimatedString result
    Corresponds to attribute result on the given element.

### Interface SVGFEBlendElement

The SVGFEBlendElement interface corresponds to the 'feBlend' element.

IDL Definition

      interface SVGFEBlendElement :
                      SVGElement,
                      SVGFilterPrimitiveStandardAttributes {

        // Blend Mode Types
        const unsigned short SVG_FEBLEND_MODE_UNKNOWN  = 0;
        const unsigned short SVG_FEBLEND_MODE_NORMAL   = 1;
        const unsigned short SVG_FEBLEND_MODE_MULTIPLY = 2;
        const unsigned short SVG_FEBLEND_MODE_SCREEN   = 3;
        const unsigned short SVG_FEBLEND_MODE_DARKEN   = 4;
        const unsigned short SVG_FEBLEND_MODE_LIGHTEN  = 5;

        readonly attribute SVGAnimatedString      in1;
        readonly attribute SVGAnimatedString      in2;
        readonly attribute SVGAnimatedEnumeration mode;
      };

Definition group Blend Mode Types
  Defined constants

    SVG_FEBLEND_MODE_UNKNOWN |  | The type is not one of predefined types. It is invalid to attempt to define a new value of this type or to attempt to switch an existing value to this type.
    SVG_FEBLEND_MODE_NORMAL |  | Corresponds to value normal.
    SVG_FEBLEND_MODE_MULTIPLY |  | Corresponds to value multiply.
    SVG_FEBLEND_MODE_SCREEN |  | Corresponds to value screen.
    SVG_FEBLEND_MODE_DARKEN |  | Corresponds to value darken.
    SVG_FEBLEND_MODE_LIGHTEN |  | Corresponds to value lighten.

Attributes
  readonly SVGAnimatedString in1
    Corresponds to attribute in on the given 'feBlend' element.
  readonly SVGAnimatedString in2
    Corresponds to attribute in2 on the given 'feBlend' element.
  readonly SVGAnimatedEnumeration mode
    Corresponds to attribute mode on the given 'feBlend' element. Takes one of the Blend Mode Types.

### Interface SVGFEColorMatrixElement

The SVGFEColorMatrixElement interface corresponds to the 'feColorMatrix' element.

IDL Definition

      interface SVGFEColorMatrixElement :
                      SVGElement,
                      SVGFilterPrimitiveStandardAttributes {

        // Color Matrix Types
        const unsigned short SVG_FECOLORMATRIX_TYPE_UNKNOWN          = 0;
        const unsigned short SVG_FECOLORMATRIX_TYPE_MATRIX           = 1;
        const unsigned short SVG_FECOLORMATRIX_TYPE_SATURATE         = 2;
        const unsigned short SVG_FECOLORMATRIX_TYPE_HUEROTATE        = 3;
        const unsigned short SVG_FECOLORMATRIX_TYPE_LUMINANCETOALPHA = 4;

        readonly attribute SVGAnimatedString      in1;
        readonly attribute SVGAnimatedEnumeration type;
        readonly attribute SVGAnimatedNumberList  values;
      };

Definition group Color Matrix Types
  Defined constants

    SVG_FECOLORMATRIX_TYPE_UNKNOWN |  | The type is not one of predefined types. It is invalid to attempt to define a new value of this type or to attempt to switch an existing value to this type.
    SVG_FECOLORMATRIX_TYPE_MATRIX |  | Corresponds to value matrix.
    SVG_FECOLORMATRIX_TYPE_SATURATE |  | Corresponds to value saturate.
    SVG_FECOLORMATRIX_TYPE_HUEROTATE |  | Corresponds to value hueRotate.
    SVG_FECOLORMATRIX_TYPE_LUMINANCETOALPHA |  | Corresponds to value luminanceToAlpha.

Attributes
  readonly SVGAnimatedString in1
    Corresponds to attribute in on the given 'feColorMatrix' element.
  readonly SVGAnimatedEnumeration type
    Corresponds to attribute type on the given 'feColorMatrix' element. Takes one of the Color Matrix Types.
  readonly SVGAnimatedNumberList values
    Corresponds to attribute values on the given 'feColorMatrix' element.

    Provides access to the contents of the values attribute.

### Interface SVGFEComponentTransferElement

The SVGFEComponentTransferElement interface corresponds to the 'feComponentTransfer' element.

IDL Definition

      interface SVGFEComponentTransferElement :
                      SVGElement,
                      SVGFilterPrimitiveStandardAttributes {

        readonly attribute SVGAnimatedString in1;
      };

Attributes
  readonly SVGAnimatedString in1
    Corresponds to attribute in on the given 'feBlend' element.

### Interface SVGComponentTransferFunctionElement

This interface defines a base interface used by the component transfer function interfaces.

IDL Definition

      interface SVGComponentTransferFunctionElement : SVGElement {
        // Component Transfer Types
        const unsigned short SVG_FECOMPONENTTRANSFER_TYPE_UNKNOWN  = 0;
        const unsigned short SVG_FECOMPONENTTRANSFER_TYPE_IDENTITY = 1;
        const unsigned short SVG_FECOMPONENTTRANSFER_TYPE_TABLE    = 2;
        const unsigned short SVG_FECOMPONENTTRANSFER_TYPE_DISCRETE    = 3;
        const unsigned short SVG_FECOMPONENTTRANSFER_TYPE_LINEAR   = 4;
        const unsigned short SVG_FECOMPONENTTRANSFER_TYPE_GAMMA    = 5;

        readonly attribute SVGAnimatedEnumeration type;
        readonly attribute SVGAnimatedNumberList  tableValues;
        readonly attribute SVGAnimatedNumber      slope;
        readonly attribute SVGAnimatedNumber      intercept;
        readonly attribute SVGAnimatedNumber      amplitude;
        readonly attribute SVGAnimatedNumber      exponent;
        readonly attribute SVGAnimatedNumber      offset;
      };

Definition group Component Transfer Types
  Defined constants

    SVG_FECOMPONENTTRANSFER_TYPE_UNKNOWN |  | The type is not one of predefined types. It is invalid to attempt to define a new value of this type or to attempt to switch an existing value to this type.
    SVG_FECOMPONENTTRANSFER_TYPE_IDENTITY |  | Corresponds to value identity.
    SVG_FECOMPONENTTRANSFER_TYPE_TABLE |  | Corresponds to value table.
    SVG_FECOMPONENTTRANSFER_TYPE_DISCRETE |  | Corresponds to value discrete.
    SVG_FECOMPONENTTRANSFER_TYPE_LINEAR |  | Corresponds to value linear.
    SVG_FECOMPONENTTRANSFER_TYPE_GAMMA |  | Corresponds to value gamma.

Attributes
  readonly SVGAnimatedEnumeration type
    Corresponds to attribute type on the given element. Takes one of the Component Transfer Types.
  readonly SVGAnimatedNumberList tableValues
    Corresponds to attribute tableValues on the given element.
  readonly SVGAnimatedNumber slope
    Corresponds to attribute slope on the given element.
  readonly SVGAnimatedNumber intercept
    Corresponds to attribute intercept on the given element.
  readonly SVGAnimatedNumber amplitude
    Corresponds to attribute amplitude on the given element.
  readonly SVGAnimatedNumber exponent
    Corresponds to attribute exponent on the given element.
  readonly SVGAnimatedNumber offset
    Corresponds to attribute offset on the given element.

### Interface SVGFEFuncRElement

The SVGFEFuncRElement interface corresponds to the 'feFuncR' element.

IDL Definition

      interface SVGFEFuncRElement : SVGComponentTransferFunctionElement {};

### Interface SVGFEFuncGElement

The SVGFEFuncGElement interface corresponds to the 'feFuncG' element.

IDL Definition

      interface SVGFEFuncGElement : SVGComponentTransferFunctionElement {};

### Interface SVGFEFuncBElement

The SVGFEFuncBElement interface corresponds to the 'feFuncB' element.

IDL Definition

      interface SVGFEFuncBElement : SVGComponentTransferFunctionElement {};

### Interface SVGFEFuncAElement

The SVGFEFuncAElement interface corresponds to the 'feFuncA' element.

IDL Definition

      interface SVGFEFuncAElement : SVGComponentTransferFunctionElement {};

### Interface SVGFECompositeElement

The SVGFECompositeElement interface corresponds to the 'feComposite' element.

IDL Definition

      interface SVGFECompositeElement :
                      SVGElement,
                      SVGFilterPrimitiveStandardAttributes {

        // Composite Operators
        const unsigned short SVG_FECOMPOSITE_OPERATOR_UNKNOWN    = 0;
        const unsigned short SVG_FECOMPOSITE_OPERATOR_OVER       = 1;
        const unsigned short SVG_FECOMPOSITE_OPERATOR_IN         = 2;
        const unsigned short SVG_FECOMPOSITE_OPERATOR_OUT        = 3;
        const unsigned short SVG_FECOMPOSITE_OPERATOR_ATOP       = 4;
        const unsigned short SVG_FECOMPOSITE_OPERATOR_XOR        = 5;
        const unsigned short SVG_FECOMPOSITE_OPERATOR_ARITHMETIC = 6;

        readonly attribute SVGAnimatedString      in1;
        readonly attribute SVGAnimatedString      in2;
        readonly attribute SVGAnimatedEnumeration operator;
        readonly attribute SVGAnimatedNumber      k1;
        readonly attribute SVGAnimatedNumber      k2;
        readonly attribute SVGAnimatedNumber      k3;
        readonly attribute SVGAnimatedNumber      k4;
      };

Definition group Composite Operators
  Defined constants

    SVG_FECOMPOSITE_OPERATOR_UNKNOWN |  | The type is not one of predefined types. It is invalid to attempt to define a new value of this type or to attempt to switch an existing value to this type.
    SVG_FECOMPOSITE_OPERATOR_OVER |  | Corresponds to value over.
    SVG_FECOMPOSITE_OPERATOR_IN |  | Corresponds to value in.
    SVG_FECOMPOSITE_OPERATOR_OUT |  | Corresponds to value out.
    SVG_FECOMPOSITE_OPERATOR_ATOP |  | Corresponds to value atop.
    SVG_FECOMPOSITE_OPERATOR_XOR |  | Corresponds to value xor.
    SVG_FECOMPOSITE_OPERATOR_ARITHMETIC |  | Corresponds to value arithmetic.

Attributes
  readonly SVGAnimatedString in1
    Corresponds to attribute in on the given 'feComposite' element.
  readonly SVGAnimatedString in2
    Corresponds to attribute in2 on the given 'feComposite' element.
  readonly SVGAnimatedEnumeration operator
    Corresponds to attribute operator on the given 'feComposite' element. Takes one of the Composite Operators.
  readonly SVGAnimatedNumber k1
    Corresponds to attribute k1 on the given 'feComposite' element.
  readonly SVGAnimatedNumber k2
    Corresponds to attribute k2 on the given 'feComposite' element.
  readonly SVGAnimatedNumber k3
    Corresponds to attribute k3 on the given 'feComposite' element.
  readonly SVGAnimatedNumber k4
    Corresponds to attribute k4 on the given 'feComposite' element.

### Interface SVGFEConvolveMatrixElement

The SVGFEConvolveMatrixElement interface corresponds to the 'feConvolveMatrix' element.

IDL Definition

      interface SVGFEConvolveMatrixElement :
                      SVGElement,
                      SVGFilterPrimitiveStandardAttributes {

        // Edge Mode Values
        const unsigned short SVG_EDGEMODE_UNKNOWN   = 0;
        const unsigned short SVG_EDGEMODE_DUPLICATE = 1;
        const unsigned short SVG_EDGEMODE_WRAP      = 2;
        const unsigned short SVG_EDGEMODE_NONE      = 3;

        readonly attribute SVGAnimatedInteger     orderX;
        readonly attribute SVGAnimatedInteger     orderY;
        readonly attribute SVGAnimatedNumberList  kernelMatrix;
        readonly attribute SVGAnimatedNumber      divisor;
        readonly attribute SVGAnimatedNumber      bias;
        readonly attribute SVGAnimatedInteger     targetX;
        readonly attribute SVGAnimatedInteger     targetY;
        readonly attribute SVGAnimatedEnumeration edgeMode;
        readonly attribute SVGAnimatedLength      kernelUnitLengthX;
        readonly attribute SVGAnimatedLength      kernelUnitLengthY;
        readonly attribute SVGAnimatedBoolean     preserveAlpha;
      };

Definition group Edge Mode Values
  Defined constants

    SVG_EDGEMODE_UNKNOWN |  | The type is not one of predefined types. It is invalid to attempt to define a new value of this type or to attempt to switch an existing value to this type.
    SVG_EDGEMODE_DUPLICATE |  | Corresponds to value duplicate.
    SVG_EDGEMODE_WRAP |  | Corresponds to value wrap.
    SVG_EDGEMODE_NONE |  | Corresponds to value none.

Attributes
  readonly SVGAnimatedInteger orderX
    Corresponds to attribute order on the given 'feConvolveMatrix' element.
  readonly SVGAnimatedInteger orderY
    Corresponds to attribute order on the given 'feConvolveMatrix' element.
  readonly SVGAnimatedNumberList kernelMatrix
    Corresponds to attribute kernelMatrix on the given element.
  readonly SVGAnimatedNumber divisor
    Corresponds to attribute divisor on the given 'feConvolveMatrix' element.
  readonly SVGAnimatedNumber bias
    Corresponds to attribute bias on the given 'feConvolveMatrix' element.
  readonly SVGAnimatedInteger targetX
    Corresponds to attribute targetX on the given 'feConvolveMatrix' element.
  readonly SVGAnimatedInteger targetY
    Corresponds to attribute targetY on the given 'feConvolveMatrix' element.
  readonly SVGAnimatedEnumeration edgeMode
    Corresponds to attribute edgeMode on the given 'feConvolveMatrix' element. Takes one of the Edge Mode Types.
  readonly SVGAnimatedLength kernelUnitLengthX
    Corresponds to attribute kernelUnitLength on the given 'feConvolveMatrix' element.
  readonly SVGAnimatedLength kernelUnitLengthY
    Corresponds to attribute kernelUnitLength on the given 'feConvolveMatrix' element.
  readonly SVGAnimatedBoolean preserveAlpha
    Corresponds to attribute preserveAlpha on the given 'feConvolveMatrix' element.

### Interface SVGFEDiffuseLightingElement

The SVGFEDiffuseLightingElement interface corresponds to the 'feDiffuseLighting' element.

IDL Definition

      interface SVGFEDiffuseLightingElement :
                      SVGElement,
                      SVGStylable,
                      SVGFilterPrimitiveStandardAttributes {

        readonly attribute SVGAnimatedString in1;
        readonly attribute SVGAnimatedNumber surfaceScale;
        readonly attribute SVGAnimatedNumber diffuseConstant;
      };

Attributes
  readonly SVGAnimatedString in1
    Corresponds to attribute in on the given 'feDiffuseLighting' element.
  readonly SVGAnimatedNumber surfaceScale
    Corresponds to attribute surfaceScale on the given 'feDiffuseLighting' element.
  readonly SVGAnimatedNumber diffuseConstant
    Corresponds to attribute diffuseConstant on the given 'feDiffuseLighting' element.

### Interface SVGFEDistantLightElement

The SVGFEDistantLightElement interface corresponds to the 'feDistantLight' element.

IDL Definition

      interface SVGFEDistantLightElement : SVGElement {
        readonly attribute SVGAnimatedNumber azimuth;
        readonly attribute SVGAnimatedNumber elevation;
      };

Attributes
  readonly SVGAnimatedNumber azimuth
    Corresponds to attribute azimuth on the given 'feDistantLight' element.
  readonly SVGAnimatedNumber elevation
    Corresponds to attribute elevation on the given 'feDistantLight' element.

### Interface SVGFEPointLightElement

The SVGFEPointLightElement interface corresponds to the 'fePointLight' element.

IDL Definition

      interface SVGFEPointLightElement : SVGElement {
        readonly attribute SVGAnimatedNumber x;
        readonly attribute SVGAnimatedNumber y;
        readonly attribute SVGAnimatedNumber z;
      };

Attributes
  readonly SVGAnimatedNumber x
    Corresponds to attribute x on the given 'fePointLight' element.
  readonly SVGAnimatedNumber y
    Corresponds to attribute y on the given 'fePointLight' element.
  readonly SVGAnimatedNumber z
    Corresponds to attribute z on the given 'fePointLight' element.

### Interface SVGFESpotLightElement

The SVGFESpotLightElement interface corresponds to the 'feSpotLight' element.

IDL Definition

      interface SVGFESpotLightElement : SVGElement {
        readonly attribute SVGAnimatedNumber x;
        readonly attribute SVGAnimatedNumber y;
        readonly attribute SVGAnimatedNumber z;
        readonly attribute SVGAnimatedNumber pointsAtX;
        readonly attribute SVGAnimatedNumber pointsAtY;
        readonly attribute SVGAnimatedNumber pointsAtZ;
        readonly attribute SVGAnimatedNumber specularExponent;
        readonly attribute SVGAnimatedNumber limitingConeAngle;
      };

Attributes
  readonly SVGAnimatedNumber x
    Corresponds to attribute x on the given 'feSpotLight' element.
  readonly SVGAnimatedNumber y
    Corresponds to attribute y on the given 'feSpotLight' element.
  readonly SVGAnimatedNumber z
    Corresponds to attribute z on the given 'feSpotLight' element.
  readonly SVGAnimatedNumber pointsAtX
    Corresponds to attribute pointsAtX on the given 'feSpotLight' element.
  readonly SVGAnimatedNumber pointsAtY
    Corresponds to attribute pointsAtY on the given 'feSpotLight' element.
  readonly SVGAnimatedNumber pointsAtZ
    Corresponds to attribute pointsAtZ on the given 'feSpotLight' element.
  readonly SVGAnimatedNumber specularExponent
    Corresponds to attribute specularExponent on the given 'feSpotLight' element.
  readonly SVGAnimatedNumber limitingConeAngle
    Corresponds to attribute limitingConeAngle on the given 'feSpotLight' element.

### Interface SVGFEDisplacementMapElement

The SVGFEDisplacementMapElement interface corresponds to the 'feDisplacementMap' element.

IDL Definition

      interface SVGFEDisplacementMapElement :
                      SVGElement,
                      SVGFilterPrimitiveStandardAttributes {

        // Channel Selectors
        const unsigned short SVG_CHANNEL_UNKNOWN = 0;
        const unsigned short SVG_CHANNEL_R       = 1;
        const unsigned short SVG_CHANNEL_G       = 2;
        const unsigned short SVG_CHANNEL_B       = 3;
        const unsigned short SVG_CHANNEL_A       = 4;

        readonly attribute SVGAnimatedString      in1;
        readonly attribute SVGAnimatedString      in2;
        readonly attribute SVGAnimatedNumber      scale;
        readonly attribute SVGAnimatedEnumeration xChannelSelector;
        readonly attribute SVGAnimatedEnumeration yChannelSelector;
      };

Definition group Channel Selectors
  Defined constants

    SVG_CHANNEL_UNKNOWN |  | The type is not one of predefined types. It is invalid to attempt to define a new value of this type or to attempt to switch an existing value to this type.
    SVG_CHANNEL_R |  | Corresponds to value R.
    SVG_CHANNEL_G |  | Corresponds to value G.
    SVG_CHANNEL_B |  | Corresponds to value B.
    SVG_CHANNEL_A |  | Corresponds to value A.

Attributes
  readonly SVGAnimatedString in1
    Corresponds to attribute in on the given 'feDisplacementMap' element.
  readonly SVGAnimatedString in2
    Corresponds to attribute in2 on the given 'feDisplacementMap' element.
  readonly SVGAnimatedNumber scale
    Corresponds to attribute scale on the given 'feDisplacementMap' element.
  readonly SVGAnimatedEnumeration xChannelSelector
    Corresponds to attribute xChannelSelector on the given 'feDisplacementMap' element. Takes one of the Channel Selectors.
  readonly SVGAnimatedEnumeration yChannelSelector
    Corresponds to attribute yChannelSelector on the given 'feDisplacementMap' element. Takes one of the Channel Selectors.

### Interface SVGFEFloodElement

The SVGFEFloodElement interface corresponds to the 'feFlood' element.

IDL Definition

      interface SVGFEFloodElement :
                      SVGElement,
                      SVGStylable,
                      SVGFilterPrimitiveStandardAttributes {

        readonly attribute SVGAnimatedString      in1;
      };

Attributes
  readonly SVGAnimatedString in1
    Corresponds to attribute in on the given 'feBlend' element.

### Interface SVGFEGaussianBlurElement

The SVGFEGaussianBlurElement interface corresponds to the 'feGaussianBlur' element.

IDL Definition

      interface SVGFEGaussianBlurElement :
                      SVGElement,
                      SVGFilterPrimitiveStandardAttributes {

        readonly attribute SVGAnimatedString in1;
        readonly attribute SVGAnimatedNumber stdDeviationX;
        readonly attribute SVGAnimatedNumber stdDeviationY;

        void setStdDeviation ( in float stdDeviationX, in float stdDeviationY );
      };

Attributes
  readonly SVGAnimatedString in1
    Corresponds to attribute in on the given 'feGaussianBlur' element.
  readonly SVGAnimatedNumber stdDeviationX
    Corresponds to attribute stdDeviation on the given 'feGaussianBlur' element. Contains the X component of attribute stdDeviation.
  readonly SVGAnimatedNumber stdDeviationY
    Corresponds to attribute stdDeviation on the given 'feGaussianBlur' element. Contains the Y component (possibly computed automatically) of attribute stdDeviation.
Methods
  setStdDeviation
    Sets the values for attribute stdDeviation.
    Parameters

      in float stdDeviationX |  | The X component of attribute stdDeviation.
      in float stdDeviationY |  | The Y component of attribute stdDeviation.

    No Return Value
    No Exceptions

### Interface SVGFEImageElement

The SVGFEImageElement interface corresponds to the 'feImage' element.

IDL Definition

      interface SVGFEImageElement :
                      SVGElement,
                      SVGURIReference,
                      SVGLangSpace,
                      SVGExternalResourcesRequired,
                      SVGStylable,
                      SVGTransformable,
                      SVGFilterPrimitiveStandardAttributes {};

### Interface SVGFEMergeElement

The SVGFEMergeElement interface corresponds to the 'feMerge' element.

IDL Definition

      interface SVGFEMergeElement :
                      SVGElement,
                      SVGFilterPrimitiveStandardAttributes {};

### Interface SVGFEMergeNodeElement

The SVGFEMergeNodeElement interface corresponds to the 'feMergeNode' element.

IDL Definition

      interface SVGFEMergeNodeElement : SVGElement {
        readonly attribute SVGAnimatedString in1;
      };

Attributes
  readonly SVGAnimatedString in1
    Corresponds to attribute in on the given 'SVGFEMergeNodeElement' element.

### Interface SVGFEMorphologyElement

The SVGFEMorphologyElement interface corresponds to the 'feMorphology' element.

IDL Definition

      interface SVGFEMorphologyElement :
                      SVGElement,
                      SVGFilterPrimitiveStandardAttributes {

        // Morphology Operators
        const unsigned short SVG_MORPHOLOGY_OPERATOR_UNKNOWN = 0;
        const unsigned short SVG_MORPHOLOGY_OPERATOR_ERODE   = 1;
        const unsigned short SVG_MORPHOLOGY_OPERATOR_DILATE  = 2;

        readonly attribute SVGAnimatedString      in1;
        readonly attribute SVGAnimatedEnumeration operator;
        readonly attribute SVGAnimatedLength      radiusX;
        readonly attribute SVGAnimatedLength      radiusY;
      };

Definition group Morphology Operators
  Defined constants

    SVG_MORPHOLOGY_OPERATOR_UNKNOWN |  | The type is not one of predefined types. It is invalid to attempt to define a new value of this type or to attempt to switch an existing value to this type.
    SVG_MORPHOLOGY_OPERATOR_ERODE |  | Corresponds to value erode.
    SVG_MORPHOLOGY_OPERATOR_DILATE |  | Corresponds to value dilate.

Attributes
  readonly SVGAnimatedString in1
    Corresponds to attribute in on the given 'feMorphology' element.
  readonly SVGAnimatedEnumeration operator
    Corresponds to attribute operator on the given 'feMorphology' element. Takes one of the Morphology Operators.
  readonly SVGAnimatedLength radiusX
    Corresponds to attribute radius on the given 'feMorphology' element.
  readonly SVGAnimatedLength radiusY
    Corresponds to attribute radius on the given 'feMorphology' element.

### Interface SVGFEOffsetElement

The SVGFEOffsetElement interface corresponds to the 'feOffset' element.

IDL Definition

      interface SVGFEOffsetElement :
                      SVGElement,
                      SVGFilterPrimitiveStandardAttributes {

        readonly attribute SVGAnimatedString in1;
        readonly attribute SVGAnimatedLength dx;
        readonly attribute SVGAnimatedLength dy;
      };

Attributes
  readonly SVGAnimatedString in1
    Corresponds to attribute in on the given 'feOffset' element.
  readonly SVGAnimatedLength dx
    Corresponds to attribute dx on the given 'feOffset' element.
  readonly SVGAnimatedLength dy
    Corresponds to attribute dy on the given 'feOffset' element.

### Interface SVGFESpecularLightingElement

The SVGFESpecularLightingElement interface corresponds to the 'feSpecularLighting' element.

IDL Definition

      interface SVGFESpecularLightingElement :
                      SVGElement,
                      SVGStylable,
                      SVGFilterPrimitiveStandardAttributes {

        readonly attribute SVGAnimatedString in1;
        readonly attribute SVGAnimatedNumber surfaceScale;
        readonly attribute SVGAnimatedNumber specularConstant;
        readonly attribute SVGAnimatedNumber specularExponent;
      };

Attributes
  readonly SVGAnimatedString in1
    Corresponds to attribute in on the given 'feSpecularLighting' element.
  readonly SVGAnimatedNumber surfaceScale
    Corresponds to attribute surfaceScale on the given 'feSpecularLighting' element.
  readonly SVGAnimatedNumber specularConstant
    Corresponds to attribute specularConstant on the given 'feSpecularLighting' element.
  readonly SVGAnimatedNumber specularExponent
    Corresponds to attribute specularExponent on the given 'feSpecularLighting' element.

### Interface SVGFETileElement

The SVGFETileElement interface corresponds to the 'feTile' element.

IDL Definition

      interface SVGFETileElement :
                      SVGElement,
                      SVGFilterPrimitiveStandardAttributes {

        readonly attribute SVGAnimatedString in1;
      };

Attributes
  readonly SVGAnimatedString in1
    Corresponds to attribute in on the given 'feTile' element.

### Interface SVGFETurbulenceElement

The SVGFETurbulenceElement interface corresponds to the 'feTurbulence' element.

IDL Definition

      interface SVGFETurbulenceElement :
                      SVGElement,
                      SVGFilterPrimitiveStandardAttributes {

        // Turbulence Types
        const unsigned short SVG_TURBULENCE_TYPE_UNKNOWN      = 0;
        const unsigned short SVG_TURBULENCE_TYPE_FRACTALNOISE = 1;
        const unsigned short SVG_TURBULENCE_TYPE_TURBULENCE   = 2;
        // Stitch Options
        const unsigned short SVG_STITCHTYPE_UNKNOWN  = 0;
        const unsigned short SVG_STITCHTYPE_STITCH   = 1;
        const unsigned short SVG_STITCHTYPE_NOSTITCH = 2;

        readonly attribute SVGAnimatedNumber      baseFrequencyX;
        readonly attribute SVGAnimatedNumber      baseFrequencyY;
        readonly attribute SVGAnimatedInteger     numOctaves;
        readonly attribute SVGAnimatedNumber      seed;
        readonly attribute SVGAnimatedEnumeration stitchTiles;
        readonly attribute SVGAnimatedEnumeration type;
      };

Definition group Turbulence Types
  Defined constants

    SVG_TURBULENCE_TYPE_UNKNOWN |  | The type is not one of predefined types. It is invalid to attempt to define a new value of this type or to attempt to switch an existing value to this type.
    SVG_TURBULENCE_TYPE_FRACTALNOISE |  | Corresponds to value fractalNoise.
    SVG_TURBULENCE_TYPE_TURBULENCE |  | Corresponds to value turbulence.

Definition group Stitch Options
  Defined constants

    SVG_STITCHTYPE_UNKNOWN |  | The type is not one of predefined types. It is invalid to attempt to define a new value of this type or to attempt to switch an existing value to this type.
    SVG_STITCHTYPE_STITCH |  | Corresponds to value stitch.
    SVG_STITCHTYPE_NOSTITCH |  | Corresponds to value noStitch.

Attributes
  readonly SVGAnimatedNumber baseFrequencyX
    Corresponds to attribute baseFrequencyX on the given 'feTurbulence' element.
  readonly SVGAnimatedNumber baseFrequencyY
    Corresponds to attribute baseFrequencyY on the given 'feTurbulence' element.
  readonly SVGAnimatedInteger numOctaves
    Corresponds to attribute numOctaves on the given 'feTurbulence' element.
  readonly SVGAnimatedNumber seed
    Corresponds to attribute seed on the given 'feTurbulence' element.
  readonly SVGAnimatedEnumeration stitchTiles
    Corresponds to attribute stitchTiles on the given 'feTurbulence' element. Takes one of the Stitching Options.
  readonly SVGAnimatedEnumeration type
    Corresponds to attribute type on the given 'feTurbulence' element. Takes one of the Turbulence Types.

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