Re: meeting minutes 4/4/2013

On 05-04-13 00:32, Dirk Schulze wrote:
> ...
>    <scribe> ACTION: Tav produce an exmaple, demonstrating how
>    different color space interpolation effects image scaling
>    [recorded in
>    [13]http://www.w3.org/2013/04/04-svg-minutes.html#action02]
> 
>    <trackbot> Created ACTION-3481 - Produce an exmaple,
>    demonstrating how different color space interpolation effects
>    image scaling [on Tavmjong Bah - due 2013-04-11].

In case you're interested, this has a nice discussion of the effect of
gamma on resizing images:
http://www.4p8.com/eric.brasseur/gamma.html
As far as I can tell this is the main issue with the bitmap part, and
I'd say it's excusable, given that SVG currently at least seems to
suggest doing this kind of operation in sRGB. (Although this might
indeed be something to work on.)

The issue with the top-right square is quite interesting. My guess is
that it's related to the "seams" problem that you see when you two not
quite pixel-aligned boundaries right next to each other, in that this
problem probably also stems from an imperfect estimation of the coverage
values because of not being able to determine whether different parts of
the image overlap or not. I'd love to hear what you find, as I cannot
quite put my finger on how exactly the observed value is arrived at.
(Without basically retracing the steps of the rasterization algorithm.)

BTW, I attached a modification of Tav's test file that shows that it is
indeed at least partly related to the fact that you used two different
shapes for the checkerboard pattern. (I also changed the transforms and
grouping a bit, but I verified that this doesn't change the result.)