Greg Sullivan wrote:
Graeme wrote:
If I try and reproduce spot colors on the display using
ICCabsolute, hoping to be able to check for an exact match
(as supposedly ICCabsolute is intended), then they won't
match - the display output will be too blue.
I thought that was the intent of ICCabsolute as well, but when I spoke
directly with a representative of the ICC about this some time ago, they
denied this, at least as far as displays are concerned. They explained that
in order to achieve what we want to achieve, we must determine the real
colorimetry first (using the chad tag, for example), and go from
there. But the ICC don't call this ICCabsolute.
If this is in fact the case, then it's really asking for trouble.
Most of those who have learnt something about color, have been
taught that "Absolute Colorimetric is used for proofing and
spot colors". As well, this is contradicted by the ICC spec. itself:
ICC V4.2 page 8:
"The media-relative colorimetric transform is useful for colours
that have already been mapped to the intended reproduction
media-relative colorimetry, whereas the ICC-absolute colorimetric
transform is useful for spot colours, and when simulating one
medium on another in proofing applications."
So what should one believe ?
The reason for my own interest in this topic is that when I purchased the
Eye One Display product, and noticed that an absolute conversion from, say,
a D50 whitepoint to a D65 monitor produced a D65 result, I threw my arms
up in the air and exclaimed that Eye One Display was producing buggy
profiles. (as some of you will recall ;^) I think I ended up being satisfied
that the Eye One Profiles aren't really buggy, although I wished that
they included the 'chad' tag.
Right, they're not buggy, they're just ICC V4 :- incompatible with everything
that came before ! :-)
Graeme Gill.
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