Re: Rendering Intents
Re: Rendering Intents
- Subject: Re: Rendering Intents
- From: bruce fraser <email@hidden>
- Date: Mon, 2 Sep 2002 22:08:57 -0700
At 12:12 PM +1000 9/2/02, Graeme Gill wrote:
bruce fraser wrote:
It's not really an ICC profile limitation, it's a corollary of the
"smart profile/dumb CMM" architecture of ICC color management.
It seems to also be patterned after the way Postscript handles
color, as it to, doesn't seem to have any expectation that "real"
gamut mapping will be performed.
I've never seen Postscript color management work in any practical
way. You can only load one CRD per job, so you get a
one-size-fits-all rendering on the output side. (And that's if we
even had tools for loading CRDs!)
Sorry, I don't follow this line or reasoning. Given that both the
A2B and B2A tables may change the gamut, and given
that in general you will be mixing and matching source and
destination profiles from different CMMs, there seems a very
large scope indeed for poor results. Consider the situation
in which CMM A takes the line of using the A2B table to
expand or compress to its standard gamut (which happens to
be, say, the SWOP colorspace) and sets up its B2A table to
assume that it is being fed from one of its own profiles,
mixed with CMM B, which assumes that the A2B table doesn't
change the gamut, and that it has to compress from a gamut
that exceeds a "super" RGB monitor.
If you use perceptual renderings in and out of the PCS, all bets are
off unless you've been very careful to build matched sets of
profiles. But relcol renderings generally give predictable results
between different profiling packages and different CMMs. Relcol in
and Perceptual out usually doesn't create too many headaches either.
But given the composition of the ICC, it's somewhat amazing that they
managed to reach the degree of consensus that they have...
If you have any way of using the resulting ICC device link profile,
I'd be happy to link a couple of your profiles using my CMS, and send
you the results, so you can make a judgement.
Let me think about how I could implement that. I'll get back to you.
I *would* like to try it.
Bruce
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