[argyllcms] Re: Generated camera profile too bright

  • From: Elle Stone <l.elle.stone@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Tue, 3 Apr 2012 10:46:07 -0400

Hi Andreas,

I downloaded your files and used xicclu to examine your profile. I
posted the xicclu curves and command line output on a temporary web
page here:


The problem seems to be that your target shot is almost a full stop
underexposed from where it would need to be to have the white patch be
above 200 RGB values (on an 8-bit RGB scale). So the icc profile
compensates by brightening the values to bring the white patch up to
near 255. If you want to use the profile, the procedure is to apply
negative exposure compensation during raw processing to bring all the
RGB values to below 40 (you can rely on what the image looks like, no
need to eye-dropper around unless you want to, a histogram should be
sufficient guide). Then when you apply your profile all the RGB values
will brighten up to where they should be and then you can convert to
your working space.

Above procedure works with UFRaw, RawTherapee, etc. I've never used

Or you could apply about a full stop's worth of positive exposure
compensation during raw processing of your target shot and reprofile.
Or reshoot the target so it doesn't need so much positive exposure

Hopefully some of the above helps and I haven't led you astray.
Elle Stone

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