[argyllcms] Re: Camera Profiling using ArgyllCMS

  • From: "Hal V. Engel" <hvengel@xxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 26 Nov 2008 18:31:33 -0800

On Wednesday 26 November 2008 18:08:25 Graeme Gill wrote:
> Hal V. Engel wrote:
> I'm not sure what you mean by a red channel reversal - there is none
> in the per channel curves, perhaps you mean the CLUT ?

Yes the inflection in the low end of the red curve in the CLUT that is evident 
when you run xicclu -fif -g -ir lprof.icc .

> The source of such a reversal will be in the patch data. 

Possibly but it is only evident in the LProf profile and if it were in the 
patch data I would expect it to show up in all three profiles to some extent.  
It could also be an issue with the LProf algorithm not handling the end of the 
curve correctly perhaps because there is not much patch data to work with near 
the end of the curve or perhaps because the dark patches are so noisy.

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