[argyllcms] Perceptual intent

  • From: <robert@xxxxxxxxxxxxxxxxxx>
  • To: <argyllcms@xxxxxxxxxxxxx>
  • Date: Tue, 16 Dec 2014 10:38:41 -0000

Hi Graeme,

I sent you some information about a profile that I thought had a problem
with the perceptual mapping.  However, on looking at other profiles I find
that the perceptual mapping in Argyll shows the same issue with all of them.

For example, here is a comparison between a paper profiled with i1Profiler
and one profiled with Argyll:

i1Profiler Colorimetric:  DMax 2.44, Volume: 93,000
Argyll Colorimetric:      DMax 2.5,  Volume: 97,000

i1Profiler Perceptual:    DMax 2.46, Volume: 92,000
Argyll Perceptual:        DMax 2.08, Volume: 90,000

This is from Beta RGB, with Beta RGB specified in colprof (i1Profiler
doesn't require a source profile to be specified).  As you can see, the
colorimetric mapping is excellent in Argyll, whereas the perceptual mapping
is not at all good.

It seems as though your interpretation of Perceptual is very strict, with an
overall squeezing in of the out-of-gamut colors.  This results in a lower
gamut volume ... and, more critically, a very much lower DMax.

Is this correct, or is there a bug in the software?  I've sent you all the
data so you should be able to see if I am doing something wrong.

If this is not a bug and not a user error, then, IMO, the perceptual mapping
in Argyll is almost unusable as is.


Other related posts: