[argyllcms] help with camera profile

  • From: Alberto Ferrante <alberto.ferrante@xxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 18 Jul 2012 23:24:49 +0200

Hi all,
I am trying to build a camera profile for a Canon 5D MKIII and it is
proving to be much harder than with the other cameras that I profiled in
the past. I am working on a profile to be used with Ufraw.
For the other cameras I was using a non-linear profile (gamma 0.45,
linearity 0.10) built with the following colprof parameters:
-qu -bn -y -al -nc -u
With these profiles on the 5D I obtain a profile that works well with
highlights, but has problems with the black point: the images look foggy
and they require manual black point compensation. Furthermore, the
"black" is not black but it has some color cast (if I measure it I get
something like red 15, blue and green 4). Even more, when using a
profile obtained with the -u option (which I used with success with
other profiles) I cannot get any value above around 250 even burning the
whole image.

The profile that seems to work best is a linear profile obtained with
the following colprof parameters:
-qu -y -am -bn -nc
Even if it is a bit flat and it brings out a yellish cast in some
lightning conditions (that can, anyway, be corrected by changing the
white balance).

I have tried all the possible profile kinds, both by using the -u flag
and not using it. I even tried with -U with no success. The black point
problem is especially annoying and I cannot get rid of it with most of
the modes (S and m seem to work better than other modes, especially
without -u).

Any comment or suggestion related to the problems above (especially the
one with black point) will be highly appreciated.



Home page: http://www.alari.ch/people/alberto
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