Uniform Perceptual Lab space v2
Uniform Perceptual Lab space v2
- Subject: Uniform Perceptual Lab space v2
- From: Tim Vitale <email@hidden>
- Date: Tue, 24 Feb 2004 13:09:42 -0800
I don't know what happened to the first one of these, looks like the
headers got mixed, but is here is a correct version...
I discovered an adaptation of CIE Lab color space some time ago on Bruce
Lindbloom's website. The discussion on its use describes the problems
that I have been having with printer output. Saturated blues go purple,
saturated reds go orange and images with little more than shades of
yellow are under saturated. According to Lindbloom's Munsell Display
Calculator, all of these problems are due to non-uniformities in the CIE
Lab color space, which are made manifest during gamut correction. He
created a Uniform Lab space which straightened the constant hue radials
and makes spheres out of constant chroma rings. If I could just use it...
I have been trying to find a way of applying this UPLab space after
Device>Lab (A2B*), so that the gamut corrections will be uniform when
the Lab>Device (B2A*) conversion occurs. Clearly this is beyond my
abilities, but I was wondering if anyone knows of a tool to manipulate
profiles in this way. Could it be as simple as adding another tag, such
as an B2B and copying the text from the Lindbloom UPLab profile to the
output profile -- see how much I don't know.
Lindbloom suggests that only developers could use his Lab-Lab profile. I
believe him because I can't find anything, outside of the OS 10
ColorSync Utility, that will open his L-L profile.
Is any developer considering making use of this Lab-Lab conversion
process? If they did, they would solve most of the problems which force
me to proof and reproof, over and over, depending on how many of the
issue noted above the particular image contains.
Tim Vitale
Conservator
Emeryville, CA
510-594-8277
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