Re: ICC v4, was: Gretag's IQueue 140 not processing correctly with V4 profiles
Re: ICC v4, was: Gretag's IQueue 140 not processing correctly with V4 profiles
- Subject: Re: ICC v4, was: Gretag's IQueue 140 not processing correctly with V4 profiles
- From: Graeme Gill <email@hidden>
- Date: Mon, 21 Nov 2005 10:53:30 -0800
Chris Murphy wrote:
Graeme Gill wrote:
If I want good reproduction using V2 and a "dumb" CMM, then I'll
>> make sure that the destination profile gamut mapping is explicitly
>> configured for mapping the source profiles gamut.
Most profiling tools (the vast majority) on the market have no clue,
and no means to give them one, about the source profile. Therefore they
have no idea what the source profile gamut is.
Yes.
And the problem with doing so is that if you have an image in sRGB,
duplicate it, convert the copy into ProPhoto RGB, you have two images
with identical colorimetric definition for the image contained inside
two very different gamuts. Any gamut mapping routing predicated on the
source gamut rather than the actual colors in the image is doing to
render those two identical images differently, perhaps so different
that it would be unacceptable.
I don't see it that way. It really doesn't matter what device colorspace
the image is in, if it remains colorimetricaly identical. As long as
the appropriate source profile is used with the image (presumably embedded
in it), then the destination profile "sees" the same gamut, and the
same gamut mapping would be appropriate (as in your example above).
Of course, if in the process of converting the image to be in a different
colorspace, it gets re-rendered in some way (ie. the new colorspace has a
smaller gamut, or the image colors are expanded to fill a larger gamut
colorspace etc.), then the same gamut mapping assumed by the destination
profile will not work so well.
Graeme Gill.
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