Re: null match
Re: null match
- Subject: Re: null match
- From: Chris Murphy <email@hidden>
- Date: Fri, 12 Jul 2002 09:15:38 -0600
Graeme Gill <email@hidden> writes:
>
Oh, I think I know what your talking about now, but it is not relevant
>
to the discussion.
You made it relevant by directing the following to John Zimmerer:
>
>You haven't answered the issue though, about how one can use the
>
>often essential side effects (like ink limiting) of processing
>
>the pixels through the profiles.
You said that was the issue. Now you're saying it's not relevant.
>
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
I'd like to know what sequence of steps allows you to use the same
profile as source and destination and you end up with different CMYK
values than you started with. I'm unable to reproduce this in Photoshop
with either ACE or the AppleCMM selected. I get the same values, no
matter the rendering intent.
>
(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.
Some users want/expect all kinds of things they can't have. This is one
of them. If they want a conversion to occur where the source and
destination are the same, they will first need to convert to an interim
space, or they can use a device link profile.
>
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.)
Have you sent them feedback? They were soliciting feedback a number of
months ago.
>
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).
Actually it also doesn't say that null matches MUST be honored through
conversion. To cause a conversion when source and destination are the
same by default is bad for workflow. It causes unnecessary conversions,
by default. It's safer for a conversion to not occur by default. If
you're looking to ensure ink limits have been honored, there's software
specifically designed to do this.
Chris Murphy
Color Remedies (tm)
Boulder, CO
303-415-9932
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