[argyllcms] Re: Custom Illuminant

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 10 Jul 2014 11:34:31 +1000

robert@xxxxxxxxxxxxxxxxxx wrote:

> Well, yes, of course I would much prefer to do a 1-step with a smaller gamut
> but I wasn't able to generate the smaller-gamut profile.  I have tried to do
> this using tiffgamut and colprof with -g, but the gamut appears identical
> with or without the -g (viewing the icc profiles using viewgam and also
> GamutVision from Imatest).

Hi,
        I'm not sure what you mean. The idea is to generate
an ICC profile that does gamut mapping from the smaller source
to the device gamut. Naturally this doesn't change the device
gamut itself, just the mapping.

> I assumed that the effect of the -g was not to reduce the size of the gamut,
> but rather to improve the efficiency of the gamut mapping.

You are confusing different things.

> tiffgamut -v -w -pj -k -cmd -Omygam.gam t1.jpg t1.jpg t2.jpg t3.jpg

> What is also interesting/puzzling is that mygam.gam is made from very
> desaturated images, and yet its gamut is bigger in places than
> HP_Z3100_CANSONPHOTOHIGLOSS_ARGYLL_LG.icc (iccgamut/viewgam).

> The Photoshop
> gamut warning does not show any of the three images as being out of gamut
> for HP_Z3100_CANSONPHOTOHIGLOSS_ARGYLL_LG.icc

That depends rather a lot on what Photoshop is doing.

If the gamut you get from tiffgamut is large, then I'm more inclined to believe 
that.

Graeme Gill.



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