[argyllcms] Re: conjgrad failed

Mickael Profeta wrote:

You are right, the problem is certainly that one.
Yet it seems it loses this step.

If I add the -a flag, it asks to place the instrument on a black surface
(which was not asked before), the first measurement looks fine, but when
it really starts the calibration in itself, the black value seems odd,
not taking into account the first step?


I guess I'm confused. Your first post indicated that you
had invoked dispcal with -a as well, and it asked you to put the
instrument on a dark surface:

From Mickael Profeta on 5/08/2006 6:30 
:~/test32/bin$ ./dispcal -i92 -a ../log/test
Offset calibration:
Place instrument on a dark surface.
Hit Esc to skip, any other key to start calibration:
Offset calibration successful
The instrument can be removed from the dark surface.
Cell ratio calibration:
Place instrument on test window.
Hit Esc to skip, any other key to start calibration:
Cell ratio calibration successful
The instrument can be removed from the screen.
Place instrument on test window.
Hit Esc to give up, any other key to continue:



here is a typical output:

alezan:/home/mike/argyll3/argyll-0.60/spectro# ./dispcal -i92 -a -v
/tmp/targen
Setting up the instrument
Offset calibration:
Place instrument on a dark surface.
Hit Esc to skip, any other key to start calibration:
Offset calibration successful
The instrument can be removed from the dark surface.
Cell ratio calibration:
Place instrument on test window.
Hit Esc to skip, any other key to start calibration:
Cell ratio calibration successful
The instrument can be removed from the screen.
Setting up the instrument
Place instrument on test window.
Hit Esc to give up, any other key to continue:
Target white = native white
Target brightness = native brightness
Target gamma = 2.200000

Press 1 .. 7
1) Black level (CRT: Brightness)
2) White point (Color temperature, R,G,B, Gain)
3) White level (CRT: Contrast, LCD: Brightness)
4) Black point (R,G,B, Offset)
5) Check all
6) Continue on to calibration
7) Exit
Doing check measurements

  Current Brightness = 70.57
  Target 50% Level  = 15.36, Current = 13.99, error = -1.9%
  Target Near Black =  0.71, Current =  0.99, error =  0.4%
  Current white = x 0.3224, y 0.3284, VDT 6251K DE  6.7
  Target black = x 0.3224, y 0.3284, Current = x 0.5879, y 0.3333, error
= 33.35 DE


This seems a fairly normal set of readings.

Press 1 .. 7
1) Black level (CRT: Brightness)
2) White point (Color temperature, R,G,B, Gain)
3) White level (CRT: Contrast, LCD: Brightness)
4) Black point (R,G,B, Offset)
5) Check all
6) Continue on to calibration
7) Exit
Commencing device calibration
patch 6 of 6
Black = XYZ 999.99   0.00 999.99
Red   = XYZ  31.09  14.61   0.22
Green = XYZ  24.39  47.13   6.82
Blue  = XYZ  12.22   3.31  59.62
White = XYZ  69.46  70.51  75.29
patch 64 of 64
Initial native brightness target = 70.510000 cd/m^2
Had to scale brightness from 70.510000 to 70.362598 to fit within gamut
Target white value is XYZ 69.314793 70.362598 75.132606
Target black point = nan 0.000000 nan
Gamma curve offset = 0.000000
Creating initial calibration curves...
dispcal: Error - Conjgrad failed


Hmm. I have no idea why the black value is so wrong. I am unable
to reproduce this with my DTP92 or DTP94.

Which platform are you running on ?

If you run with the -D flag, and capture stderr to
the logfile as well, what does the log look like ?

Graeme Gill.


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