[argyllcms] Re: Question regarding gamut mapping for photographic images

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Tue, 18 Oct 2005 14:31:19 +1000

Greg Sullivan wrote:

I'm trying to understand how Argyll is similar. As far as I can see, the
gamut expansation operation for any given source colour should be in
proportion to how much wider the destination profile's gamut is. Taking cyans, for example, the operation should greatly expand the cyans of
an sRGB source for a typical inkjet destination. And for blues, it should in fact contract the gamut, because the destination gamut is smaller.
Can Argyll really do this "morphing" of the gamut in this fashion?

Yes. "perceptual" maps the source gamut such that it is compressed to fit within the destination gamut. "saturation" compresses and expands the source gamut to make it match the destination gamut.

To go any further in understanding how it works, you would need
to compile the gamut/gammap.c code with PLOT_GAMVEC and PLOT_GAMUTS
#defined, and examine the resulting VRML plots for typical
RGB to CMYK links using perceptual and saturation.

Graeme Gill.

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