[argyllcms] Re: using ArgylLcms to work around colorSync issues

  • From: Claas Bickeböller <lists@xxxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 18 Jun 2010 15:49:39 +0200

Hi Michael,

maybe I didn't understand your task but if it's only to have a display profile
with "generic" primaries and a certain target gamma you could use the OS X 
built-in "calibration" function.
Of course this is far from accurate, but better than not doing anything if one 
doesn't have a measurement device.
I use it to make quick and dirty "calibrations" for projectors.


Am 17.06.2010 um 22:32 schrieb michael cinquin:

> Hi all
> I'm trying to work around ColorSync oddities on mac os x, with the help of 
> ArgylLcms.
> I use Apple Color, which has a strange behavior depending on the Icc Display 
> Profile that is chosen in the System Pref -> Display pane.
> On Snow Leopard, I have noticed using a scope that when using "Generic RGB 
> profile", Color displays accurately the primaries (Red, Green, Blue) and 
> secondaries (Cyan, Magenta, Green). But the gamma is wrong : the image is too 
> dark.
> If I use "Adobe RGB" as a display profile, Color displays accurately the 
> gamma, but not the colors (has been checked with a scope).
> I have found a temporary solution : using the display profile "Generic RGB", 
> and using dispwin to load a 2.2/1.8 gamma .cal file : this way the gamma and 
> the colors are correct.
> I would like to make this temporary solution more elegant : either by (A) 
> being able to modify the gamma of the "Generic RGB Profile", or (B) by 
> permanently adding a vcgt to the icc profile.
> Solution A : modifying the gamma of the "Generic RGB" Profile or building a 
> generic one from scratch
> - I saw in ColorSync Utility that the Generic RGB profile has response curves 
> with a 1.8 gamma, and I was hoping I could find a way to turn them into 2.2 
> gamma response curves (rTRC,gTRC,bTRC)
> - I was hoping there would be with synthcal and colorprof some way to build a 
> very simple synthetic icc profile, but I failed at finding a way to turn a 
> synthetic .cal file into a .ti3 file that could be used by colprof. Is this 
> possible ?
> Solution B : adding a vcgt to the "Generic RGB profile"
> - I thought I might be able to use `applycal` to add the "2.2/1.8 gamma" .cal 
> file to the "Generic RGB profile" (the .cal file is here : 
> http://pastebin.com/VAf8M8y0)
> - I tried `applycal -v -a ~/gamma_shift.cal "Generic-rgb_profile.icc 
> Generic-rgb_profile_modded.icc`, but got a seg ault
> - so I tried to use a new linear .cal file as a test, built with synthcal -t 
> d linear.cal ; but I got a seg fault again
> - I then tried to compile ArgylLcms from source (instead of the 1.1.1 
> binaries for Os X on Snow Leopard) : installed jam, cd to ArgylLcms, ran `jam 
> -q -f Jambase -j 3`, but only a few binaries compiles (the log of the compile 
> is here : http://pastebin.com/xyp5rmSb)
> I would appreciate if someone could suggest something to make solution A or B 
> work, or another solution I had not found.
> thanks
> Michael Cinquin

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