[argyllcms] Re: 0.60 CMYK profile misshaped

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Mon, 11 Dec 2006 17:43:15 +1100

Roberto Michelena wrote:
It seems to me that CIE X,Y,Z are the best choices; extend better than
densities (do not level off so quickly), are much less noisy... X for
Cyan, Y for Magenta, Z for Yellow, and any of them for Black.

Another way is the dot product with the vector to the 100% colorant
value to white (or some other choice related to the underlying
colorant vector direction) in a particular colorspace (XYZ, L*a*b* etc.).

This could be viewed as creating an "optimal" mix of the
co-ordinates as a measure, rather than just picking one
of the co-ordinates.

XYZ isn't a good choice as absolute measure, as it is
linear light, so the blacks steps will be too big.
A gamma or L* curve applied to XYZ is needed at least.

Density is a log scale, which is why it's not too bad,
although in the Colorbus calibration system I set
a target density curve corresponding to a typical
20% dot gain press curve.

Graeme Gill.

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