[argyllcms] Re: printer profiles - how to get max black

  • From: "Gerhard Fürnkranz" <nospam456@xxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 07 Dec 2006 09:03:41 +0100

-------- Original-Nachricht --------
Datum:  Thu, 07 Dec 2006 17:54:24 +1100
Von: Graeme Gill <graeme@xxxxxxxxxxxxx>
An: argyllcms@xxxxxxxxxxxxx
Betreff:  [argyllcms] Re: printer profiles - how to get max black

> The black point is rather far from neutral, which perhaps hints
> why there are issues.
> The explanation is that for out of gamut colors the closest color
> is measured in appearance space (CIECAM02 Jab space), and it's view
> of the closest point is a little different to L*a*b* space
> (that's the point of using it, so that things like blue don't
> go purple), and from a CAM02 perspective, the black point
> returned is very slightly closer to the target L*a*b* = 0,0,0
> than RGB = 0,0,0.


doesn't the gamut mapping of 0.60 now bend the perceptual gray axis at the 
lower end towards device black, such that PCS CIELAB [0,0,0] (or actually the 
BP of the supplied source color space (profile -S ...)) should eventually 
always map to device black? What am I missing?


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