2013/5/12 Carlos López González <genet...@gmail.com>
> Thanks Timotheé.
> Now I start to see things clearly. So the current situation is similar to
> the block diagram you have drawn with the exception that the user can't
> choose a color space to perform the input value of the color through the
> color chooser and that the used color profile for input and output into and
> from the Synfig core color system is always the sRGB which uses a fixed 2.2
> gamma filtering.
>
> Is that right?
>
>
Yes.
> So, what's the usage of the gamma calibration widget? Should it be
> removed? Gamma value stored in canvas in a sift file is never used and we
> use always 2.2 for output and 1/2.2 for input. If we implement the color
> management we should raise canvas version to consider those changes and
> ignore the gamma value that is now handled by littleCMS.
>
>
As said in Robert's previous email, the current gamma calibration widget
usage is for manually set color correction for the screen output (gamma per
channel and black level), and so yes it should be removed, and replace
"that old mechanism entirely with a real ICC-based color management system
would be ideal".
> I'm also worried about performance. Have littleCMS good performance
> in color conversions between profiles? Does it support premultiplied alpha
> colors?
>
> I think it has good performance, as it's used almost all other graphics
software I use and don't notice it's slowing things.
I've searched a bit and it seems it doesn't support premultiplied alpha
directly. Do you use premultiplied alpha with Cairo too?
As it's used in Inkscape and Gimp, which both use Cairo too, we can
probably make it work the same way in Synfig (and upcoming gegl-ed gimp
model with everything calculated in 32bit float linear colorspace is a bit
similar to what we have with Synfig's linear colorspace).
THOUGH I'm still wondering if .icc based color management is the right
choice for Synfig, as an animation software, it could be more logical to
integrate OpenColorIO color mangement instead.
(read at the end of this page:
http://wiki.blender.org/index.php/User:Sobotka/Color_Management )
http://opencolorio.org/developers/index.html
I have not much experience yet with this OCIO color mangement, but I guess
the concept is somehow the same as for icc based one.
I'll try to learn more about it to can push the discussion further.
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