El 12/11/12 12:50, Andrew Chadwick escribió:
Correction to my statements upthread: I think the practical answer is:
blend in device space (!), or if you want to be more predictable, blend
in nonlinear sRGB.
FWIW, Photoshop seemingly does the blending non-linearly in indexed RGB
mode, looking at the examples at http://dunnbypaul.net/blends/ and
recreating them in MyPaint master HEAD=5d100ff5 (which uses nonlinear
sRGB space for blends). Results using the two sample images are
identical, modulo dithering.
As far as I can remember (I haven't used photoshop for four years) there
was an option to select the gamma for blending.
I can't remember what was the default, but I think it was 1.0, which
would mean that Photoshop blends in linear space as default.
I'm not sure how things are supposed to be *composited* though. The
above quote doesn't answer that. I would still very much like this to be
linear :/ Perhaps you're still supposed to be explicit about compositing
space in SVG.
Every high end application out there seems to use linear, plus it's
quite easy to see the nasty effects of blending in nonlinear.
I don't know if there's a good reason behind keeping nonlinear blending,
although just blending images together without caring about their
colorspaces, assumming their gamma is 2.2 sounds like a less intensive
task than linearizing, blending and gamma correcting back.
I'm not sure if this is still relevant today, but seemed like a
reasonable question to ask. :-)
Thanks for the feedback.
Gez.
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