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Re: "Proper Gamut Mapping"



Todd Shirley wrote:
This may be an obvious question, but I have to ask it just so I'm clear: All this talk of gamut-mapping and gamut compression and color transforms really only refers to the perceptual rendering intent, correct?

Perceptual and saturation.

> What, if any, advantages do DLPs offer to colorimetric
rendering? Clearly out-of gamut colors have to be dealt with in some fashion, but do DLPs re-map these better than the 2 profile conversion method, or is it more a matter of different vendors' "secret sauce"?

There should be less secret sauce. The advantages that I see in generating device links directly for colorimetric rendering, IF the process only uses the A2B information (ie. it inverts the output profile on the fly) are:

  A much smoother, more accurate result.
  Choice of black generation parameters.
  Option of black through mapping.

I thought matrix based RGB profiles don't have ANY look-up tables, just sort of a mathematical transform based on the colorants and repro- curves, which can only give the colorimetric transform. So in that sense there are identical "tables" (in that there is only the single transform, which is called on no matter what intent you call for), but really I actually don't understand how this works, so any illumination would be greatly appreciated! How do device-links "optimize" RGB-to- CMYK transforms, considering the above?

I think you're confused. Jan-Peter Homann's statement was about matrix profiles in a conventional CMM situation. In generating device links, there's nothing special or different about matrix profiles, the fact that they represent colorimetric information is a good thing.

Graeme Gill.

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References: 
 >Re: "Proper Gamut Mapping" (From: Marco Ugolini <email@hidden>)
 >Re: "Proper Gamut Mapping" (From: Graeme Gill <email@hidden>)
 >Re: "Proper Gamut Mapping" (From: Todd Shirley <email@hidden>)
 >Re: "Proper Gamut Mapping" (From: Jan-Peter Homann <email@hidden>)
 >Re: "Proper Gamut Mapping" (From: Todd Shirley <email@hidden>)



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