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Bug 11015 - errata: feDisplacementMap needs to specify how to treat output
Summary: errata: feDisplacementMap needs to specify how to treat output
Status: NEW
Alias: None
Product: SVG
Classification: Unclassified
Component: SVG Document Object Model (DOM) (show other bugs)
Version: SVG 1.2 Tiny
Hardware: All All
: P2 normal
Target Milestone: Test Suite
Assignee: Doug Schepers
QA Contact: SVG Public List
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2010-10-12 17:15 UTC by j.chetwynd
Modified: 2010-10-17 09:42 UTC (History)
1 user (show)

See Also:


Attachments
simple testcase (622 bytes, image/svg+xml)
2010-10-12 17:15 UTC, j.chetwynd
Details

Description j.chetwynd 2010-10-12 17:15:38 UTC
Created attachment 922 [details]
simple testcase

unless style of filters is specified:
color-interpolation-filters="SRGB"

there is currently a difference in display between Mozilla and Opera or Safari.
in the attachment Mozilla lightens the filtered space, whereas Opera and Safari darken.

Robert  Longson in the Mozilla bug report says:

It all comes down to whether the output of feDisplacementMap should be
premultiplied or not.

The specification clearly says how to treat the inputs (in1 and in2)
http://www.w3.org/TR/SVG/filters.html#feDisplacementMapElement it does not say
how to treat the output. Should that be affected by color-interpolation-filters
or should it always be SRGB, LINEARRGB or whatever in1 is or even whatever in2
is.

Firefox takes the output as being whatever colour space is defined by
color-interpolation-filters i.e. if in1 starts as LINEARRGB then it finishes as
LINEARRGB. It seems like Opera and Safari assume it is SRGB.

This needs taking up with the w3c as it is unclear what is correct.

https://bugzilla.mozilla.org/show_bug.cgi?id=603584#c16
Comment 1 j.chetwynd 2010-10-12 17:16:24 UTC
mozilla  bug:
https://bugzilla.mozilla.org/show_bug.cgi?id=603584
Comment 2 Robert Longson 2010-10-17 08:11:01 UTC
in1 is the source image and in2 supplies the displacements. So it does not make sense that applying in2 should change the colour space of the output. The output colour space should be whatever in1 is.

The specification currently says this...

The color-interpolation-filters  property only applies to the in2 source image and does not apply to the in source image. The in source image must remain in its current color space.

How about something like this for extra clarity?

The color-interpolation-filters  property only applies to the in2 source image and does not apply to the in source image. The in source image must be displaced in its current color space, the output is also in that color space.
Comment 3 j.chetwynd 2010-10-17 09:27:04 UTC
#2 might this proposed change have the undesirable effect, if implemented, of changing content already published with another expectation?

might an alternative approach be to include an addendum specifying the need to add a color-interpolation-filter value to ensure consistency across browsers?
Comment 4 Robert Longson 2010-10-17 09:42:42 UTC
(In reply to comment #3)
> #2 might this proposed change have the undesirable effect, if implemented, of
> changing content already published with another expectation?
> 
> might an alternative approach be to include an addendum specifying the need to
> add a color-interpolation-filter value to ensure consistency across browsers?

No that's not appropriate It's just a workaround for what's really a bug in Firefox.