Re: null match
Re: null match
- Subject: Re: null match
- From: Chris Murphy <email@hidden>
- Date: Thu, 11 Jul 2002 21:37:34 -0600
Graeme Gill <email@hidden> writes:
>
To: email@hidden
>
Subject: Re: null match
>
>
Chris Murphy wrote:
>
> Technically this is what device link profiles are for. If the source
>
> color space is the same as the destination color space (which is what
>
> you're saying when the source profile and destination profile are the
>
> same), then it makes sense that you would get a null transformation.
>
>
Sorry I don't follow you. In what way is this "what device link profiles
>
are for" ?
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.
>
As far as I can tell, device link profile aren't "for" anything in
>
particular,
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they are just a labeling of a profile that represents a device to device
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color
>
transformation.
Conversions through a device link profile occur direct from device value
of device A to device value of device B. There is no PCS involvement.
Whenever PCS transformations occur, it's like converting the CMYK (in
this example) into LAB and then reseparating the image into CMYK. All of
the channels are lost, and there is nothing that can be done about it.
With a device link profile, channel value preservation is exactly what
they are designed for.
>
Not everyone involved in color is an institution, and has the
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funds to be a member of the ICC, and in any case, something hidden
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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.
Chris Murphy
Color Remedies (tm)
Boulder, CO
303-415-9932
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