[argyllcms] Re: Optimizing contrast to fit source gamut into device

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 16 Dec 2009 15:00:25 +1100

Nikolay Pokhilchenko wrote:
Hello, Graeme! For a long time as I start using the collink in gamut mapping 
mode, I
want ask You a contrast optimizing feature - some kind of a gamut-depended "auto
levels". In some cases the source gamut is exceeds the destination gamut only 
from top

For example take a look at http://www.colour.org/tc8-03/images/ski_pg/Ski_TC8-03_abs.tif test image. While
performing of conventional gamut mapping by collink, the output image is much 
desaturated as it may be with contrast adjusting.

Hmm. I'm not sure this is really a good fit for gamut mapping. It seems to me
that this is more like "exposure adjustment", and therefore falls outside
what "collink" is intended to do. Argyll gamut mapping very deliberately
bases it's neutral axis and white & black point adjustments on the source
colorspace, on the assumption that any image within that colorspace has
been adjusted appropriately with regard to these three attributes. Adjusting
these three attributes + general contrast is something that would need to be more heuristic, and I think would be better in a separate "auto image adjust" type

        Graeme Gill.

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