[argyllcms] Re: ArgyllCMS V1.2.0 has been released

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Tue, 03 Aug 2010 23:19:45 +1000

Nikolay Pokhilchenko wrote:
About new gamut mapping - it is the other thing now. I've noticed that the saturated areas go datrker than before at my inkjets. The improvement: the gradients with extreme saturation of colors are more balanced by tone between its ends. But the darkness of saturated colors are the drawback in some situations. I think that in general, new mapping is better, than the old one. But I should expriment and work more to understand
 the behavior of new mapping better.

Hi,

One of the fundamental choices in setting the gamut mapping is the the trade-off
between lightness and saturation. Typically the gamut mapping task is RGB to 
print,
and because these are additive and subtractive processes respectively, the most
saturated colors for print are usually much darker than RGB. So if you maintain
lightness, you can loose huge amounts of saturation (this is often very 
noticeable
in cyan), or you have to darken the tones to maintain a better degree of 
saturation.
In V1.2.0 I've opted for a little more saturation at the cost of lightness.
(You could tweak this by changing the gamut mapping numbers and recompiling.)

Another factor may be that in V1.2.0 I've paid much more attention to
maintaining the lightness level of darker colors and not lightening them
up during the mapping, in order to maintain the visual detail (The visual
detail is often conveyed by shadow details).

Graeme Gill.


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