Re: null match
Re: null match
- Subject: Re: null match
- From: Graeme Gill <email@hidden>
- Date: Fri, 12 Jul 2002 14:21:40 +1000
Chris Murphy wrote:
>
If you want to preserve the overall separation, but apply or ensure a
>
specific TAC or black ink limit, that is one of the specific uses of
>
device link profiles. If you don't want to use device link profiles, then
>
you're welcome to convert your images first to RGB or LAB, and then to
>
back to CMYK and that will apply whatever limits you set when building
>
the profile.
Oh, I think I know what your talking about now, but it is not relevant
to the discussion. I'm not talking about anything as fancy as "pass the
K separation through the conversion", or "implement proper gamut mapping",
I'm merely observing that running a CMYK value though the A2B table
of profileA, and then running the PCS through the B2A table of profileA,
will definitely give a different CMYK value than you started with, and
will have been modified in ways that a particular user may regard as desirable
(they want ink limiting, and perhaps they want the K to be regenerated).
Saying "the two profiles are the same, so I won't change the CMYK values"
is a quite different result. Some users will want/expect this,
some won't.
>
>Not everyone involved in color is an institution, and has the
>
>funds to be a member of the ICC, and in any case, something hidden
>
>on a members only web page does not constitute an international standard.
>
>
I take it you're not really familiar with the standard process at all.
>
None of the standards are free. You pay for them. Especially the ISO
>
standards. John Zimmerer said that null matches when source and
>
destination profiles are the same is the convention adopted by the ICC.
>
There's no logical reason why he would make such a thing up. So I don't
>
see why it matters that you need a citation for this.
There is a difference between a standard, available to all (maybe for
a fee), and what are essentially private discussion, available
only to those who have the (considerably larger amount of) money
available to be a member of the standards body, and attend meetings etc.
I hardly regard "John Zimmerer said.." as a standard.
The ICC has a considerable problem with its reputation in my
view, with too much "secret sauce", too many mixed up, incompletely
thought out bits that seem to be there to suite certain vendors,
but aren't complete or clear enough to be regarded as an open
international standard. (Having spent a great deal of time implementing
software that tries to comply with the standard, I think know a little bit
about it.)
Your saying that "the ICC spec. says that null matches should be ignored"
when it doesn't seem to be in the standard, doesn't help this situation.
(please correct me if I'm wrong about this).
Graeme Gill.
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