[argyllcms] Optimizing contrast to fit source gamut into device

  • From: Nikolay Pokhilchenko <nikolay_po@xxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sat, 12 Dec 2009 01:21:30 +0300

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 
or only from bottom of color space (at highlights or at darks exclusively). In 
some of that cases the contrast may be changed in an effort to the saturation. 
The contrast (the new source white point) can be optimized in such way that the 
source gamut exceeding will be more symmetrical. Therefore the source gamut 
will be a subject of a smaller degree of compression. Not all of output images 
can get the benefit from contrast optimizing, but some can get much more 
saturated and pleasant. Another idea of such feature - a smart auto-contrast 
for underexposed shots.

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 more desaturated as it may be with contrast adjusting.

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