[argyllcms] Re: Follow up to New user questions on display calibration

  • From: Klaus Karcher <lists@xxxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 20 Aug 2009 09:19:21 +0200

Hi Eric,

Eric Fishwick, CLSA wrote:
Lightroom uses a colour space called Melissa RGB which I understand has the gamut of ProPhotoRGB but with a sRGB gamma curve.

If I

-redo the screen profile with Melissa RGB as the source icc

-use Melissa RGB as the source icc for the printer profile

Would that make sense given that my aim is to get (as close as possible) a visual match between screen and printer. Most of my photography is nature photography so I suspect at some point I will have colours that are out of gamut for screen and printer.

The larger your gamut mapping source space, the more gamut compression will take place in the perceptual and saturation intents -- regardless whether your images will ever utilize the large gamut or not. Thus in many cases your results will be unnecessarily dull and desaturated. On the other hand, when your profile has been built with a gamut mapping source space smaller than the current image gamut, you will get clipping in the perceptual intent.

Therefore the choice of gamut mapping source space is always a compromise. Optimal results can only be achieved with gamut mappings adjusted to the particular application, i.e. mappings from the actually used input (image) gamut to the available output gamut.

You can use "tiffgamut" and "collink -G image.gam ..." to create device link profiles with application-specific gamut mappings (whereas there are some flaws in the current argyll version impairing the results).

Klaus

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