Re: CGATS text file from a profile
Re: CGATS text file from a profile
- Subject: Re: CGATS text file from a profile
- From: Steve Upton <email@hidden>
- Date: Thu, 17 Mar 2011 11:34:32 -0800
At 9:25 AM +0000 3/17/11, Eric Nunn wrote:
>I'd like to ask a supplemental question on this if I may.
>If I take the ISO newsprint profile - ISONewspaper26v4 - edit the whitepoint tag to reflect a Financial Times type paper colour, e.g. L81. a12. b22, I can "inject" the effect of that substrate across the whole colourspace but only if I use absolute rendering?
correct.
>So when converting from RGB if I use relative colorimetric the edit I have made makes no difference, but if I do an absolute colorimetric conversion, I can in effect "subtract" the paper colour from the colourspace.
... not sure what you mean here...
>Have I understood this correctly?
I don't think so. The white point edit is useful when the profile is used for proofing (the CMYK->Lab transform is in use). I don't think it has an effect on the rendering of the profile at all, though I could be wrong.
Are you thinking that you would like to improve the output of a profile if you adjust the profile's white point to match your paper white?
Honestly, I'm not sure. It might make a difference for abs col output but that's pretty rare in CMYK output. You often end up with D65 blue-white as the image's white which can be pretty nasty. Photoshop CS5 now overrides that white point for D65 working spaces though I haven't looked into what's really going on there.
For spot/custom colors though, it might make a difference...
worth a try
regards,
Steve
________________________________________________________________________
o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX
o email@hidden 206.985.6837
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