Re: Camera profiling with ICC et al
Re: Camera profiling with ICC et al
- Subject: Re: Camera profiling with ICC et al
- From: Graeme Gill <email@hidden>
- Date: Mon, 15 Sep 2008 23:09:21 +1000
email@hidden wrote:
A) All v2 ICC colorimetry is picture-referred and may assumed to be
output-referred. This means that all v2 ICC rendering intents represent the colorimetry
of the desired reproduction, not the scene. Yep, even for the colorimetric
rendering intent.
Hmm, I don't think so. ICC v2 profiles are perfectly capable of representing
scene referred values, since they contain pretty generic color transform
machinery, and colorimetric is certainly not meant to represent desired
reproduction, but instrument values. See the V2.4 spec A.3
"Rendering Intents" Page 68:
"The colorimetric rendering intents operate on measurement based colorimetric
values as chromatically adapted to the reference viewing environment."
and the bottom of Page 80 in section D.3 "color measurement", and see
D9, D10 and D15 page 83-85.
C) In v2, v4, and many other non-ICC profiling methods, there is no way that
I knew of to commmunicate weather the colorimetry is scene-referred or
output-referred. This means you have to assume its output-referred, the colorimetry
of the reproduction, not the scene.
Since colorimetric intent should reflect instrument measurements, you can be
pretty sure then that it is scene-referred, and only relative or saturation
intents may have had a rendering transforms applied to them (although
there are problems in doing this well without knowledge of the output
medium).
Graeme Gill.
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