[argyllcms] Am I stupid or is it something else... my color management sucks.

  • From: Magnus Berg <magnus@xxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sun, 11 Apr 2010 13:39:37 +0200

Hi, I'm new to the list and got a big problem.

I bought me a used Spyder 2. Realized that my old CTR couldn't produce enough light (90 cd/m^2 not 140 cd/m^2 that sRGB require). Digged a deep hole in my wallet and bought a quite expensive NEC 2690WUXI2. Now my color managed application show a green cast after calibration and proofing. It's not fun at all. :-(

This is how I do the calibration and proofing:

I use dispcalCUI. After that I had use the screen's OSD to set the 'White point', 'White level' and 'Black point' i got this nice values then I do a 'Check all':

Doing check measurements
Black = XYZ   2.28   7.37   0.00
Grey  = XYZ  27.17  28.58  31.02
White = XYZ 130.26 137.22 149.83
1%    = XYZ   1.38   1.46   1.58

  Target Brightness = 140.00, Current = 137.22, error = -2.0%
  Target 50% Level  = 50.07, Current = 28.58, error = -15.4%
  Target Near Black =  1.37, Current =  1.46, error =  0.1%
Target white = x 0.3128, y 0.3291, Current = x 0.3121, y 0.3288, error = 0.38 DE Target black = x 0.3128, y 0.3291, Current = x 0.3120, y 0.3299, error = 1.22 DE

Then dispcalGUI send this command to dispcal:
dispcal -v -d1 -c1 -yl -P0.500317863954,0.485345838218,1.0 -qh -t6500 -b140 -G2.2 -f0 -k0 -A4 -B0.0001 colprof -v -qh -al

Before, then I only did a -qm calibration, I got strong red casts on my calibrated screen, and the profiled applications gave strong green casts. The strange thing then was that the red cast only occurred on color 254,254,254 to around 249,249,249 but tones darker than that looked neutral grey with my eyes. After that I chose -qh this color tones and others looks neutral, with my eyes.

After that I load the calibration profile done after the command above I got this then I run dispcal -r -yl:

magnus@debian:~$ dispcal -r -yl
XRandR 1.2 is faulty - falling back to older extensions
Place instrument on test window.
Hit Esc or Q to give up, any other key to continue:
Current calibration response:
Black level = 0.60 cd/m^2
White level = 135.50 cd/m^2
Aprox. gamma = 1.92
Contrast ratio = 226:1
White chromaticity coordinates 0.3099, 0.3266
White    Correlated Color Temperature = 6676K, DE 2K to locus =  4.9
White Correlated Daylight Temperature = 6676K, DE 2K to locus =  0.3
White        Visual Color Temperature = 6490K, DE 2K to locus =  4.7
White     Visual Daylight Temperature = 6664K, DE 2K to locus =  0.3
The instrument can be removed from the screen.

I understand nothing. How can I have gamma 1.92 and the above temperature then I chose to calibrate to 2.2 and 6500? And why is there a green cast on the pictures viewed in Color managed applications?

Did I understand things right:
I should load the profile as a system wide screen calibration profile with dispcalGUI, the same as you do with dispwin -L. And then I load then same profile to the color managed applications as a screen color profile? It's then I load then profile into then color managed applications that then green cast ampere.

I have struggled with this for weeks, and googled a lot, and reading this mail list without finding any useful help. Therefor I ask you for help. The only thing I want is a good color managed environment for working with sRGB pictures.

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