[argyllcms] Re: Apple's sRGB Profile TRCs looking wrong

Samer Abdallah wrote:


Has anyone noticed that Apple's default "sRGB Profile.icc" supplied
with OS X (in /System/Library/ColorSync/Profiles) appears to have
the wrong tone response curves?

I compared it with sRGB profiles from various other sources, and
while the others all had TRCs represented as tables with 1024 entries,
containing what looked more or less like the linear-gamma function
in the specification, the Apple profile had TRCs described as
"gamma 2.199", not to mention different info the copyright and
description tags other missing information.


Yes. If I remember correctly, this was justified as a space
saving measure. There are lots of different "sRGB" profiles out there,
sowing confusion. The ICCV2 ones on the ICC website for instance,
are even more wacky. They purport to have perceptual characteristics
(ie., "black point matching") by various fudging of the curves, while
the ICC specification clearly states that matrix/shaper profiles are
always to be colorimetric.

Graeme Gill.

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