[argyllcms] Re: XYZ CLUT profiles
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Wed, 27 Jan 2010 11:41:24 +1100
Klaus Karcher wrote:
Hi Graeme,
Did you already notice that Apple's "Profile First Aid" (ColorSync
Utility) moans about missing tags in Argyll XYZ CLUT profiles?:
Tag 'rXYZ': Required tag is not present.
Tag 'gXYZ': Required tag is not present.
Tag 'bXYZ': Required tag is not present.
Tag 'rTRC': Required tag is not present.
Tag 'gTRC': Required tag is not present.
Tag 'bTRC': Required tag is not present.
I'm not exactly well versed in the ICC specs but I think Apple is wrong.
Also SampleICC's iccProfLibTest tool attests that the profile in
question is valid.
Hi Klaus,
it's unclear. The ICC V2 spec. is confusing on this issue,
since it never seems to have been edited properly when cLUT profiles
were added to the ColorSync spec. The way it reads, it's got to have
XYZ matrix tags even for L*a*b* cLUT display profiles, which is clearly
wrong, and would also be wrong if the display had less or more than
3 channels. V4 is clearer. V1.1.0 addresses this issue by adding bogus
matrix tags for XYZ cLUT profiles.
Graeme Gill.
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