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: Chris Murphy <email@hidden>
- Date: Tue, 22 Nov 2005 10:43:41 -0700
On Nov 21, 2005, at 11:53 AM, Graeme Gill wrote:
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).
That's how it works today, without respect to the source profile
used. I guess all I'm saying is that we couldn't use, say, ProPhoto
RGB as a reference medium to predicate gamut compression in the
destination profile as though any/all images could potentially
consume the entire gamut of ProPhoto. If you do that, the compromise
is going to be desaturated images that don't really use the entire
gamut of ProPhoto.
Whereas if we had dynamic gamut compression on a per image basis,
you'd have more aggressive gamut compression for an image consuming a
larger percentage of the ProPhoto RGB volume, and less aggressive
gamut compression for an image consuming a smaller percentage
(although it depends on where in the gamut that small percentage
actually is) of the ProPhoto RGB volume. I don't see how we can have
that kind of dynamic gamut mapping in a simple CMM and dumb profile
scenario like we have (largely) today.
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.
Right.
Chris Murphy
Color Remedies (TM)
www.colorremedies.com/realworldcolor
-------------------------------------------------------------
Co-author "Real World Color Management, 2nd Edition"
Published by PeachPit Press (ISBN 0-321-26722-2)
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