[argyllcms] Re: I don't understand the -u option

On Wed, 2009-02-25 at 01:40 +1100, Graeme Gill wrote:
> Leonard Evens wrote:
> > I don't seem to have much luck in choosing gamma I want.  Can you
> > suggest a reasonable strategy for accomplishing  that.   The problem
> > seems, at least in part, due to the idiosyncrasies of my monitor, a
> > Samsung 226cw.  I've tried working with the default settings and also
> > using the monitor controls, and neither approach seems to work very
> > well.  It seems that if I get one thing right, something else is bound
> > to be wrong.
> 
> Without some specific examples of what doesn't work, it's hard to
> make suggestions.

I'm not sure what a specific example would be.

But, I am attaching my TargetX.icc as well as (most of) the output when
creating it.  That file includes the settings of my Samsung monitor in
the off chance that you are familiar with it.

> 
> > Also, it seems that dispcal -r may be giving me misleading information
> > about gamma.  I believe we've discussed that before, but clearly it
> > didn't penetrate since I still don't understand it.
> 
> What makes you think you're not getting the gamma you ask for ?

When I run dispcal -r, I am told gamma is about 2.8. But I seem to get
different results by looking at various visual gamma tests, such as the
so-called amazing gamma applet.   After reading the link you provided
below, I see that a lot could depend on the actual curve the argyll
program I used produced with my articular monitor.   I am now rather
unclear on how I should decide what I want and what is accpetable.

The reason for my concern is the following.  I use gimp to modify my
digital images and regularly save the results on CDs and DVDs.  I would
like what I scan to look approximately the same when and if I, or
someone else, possibly using a different monitor and
calibration/profile, at some time in the future.  Every time I make
changes in a digital file, I lose some information, so I would like what
I ave to represent some `final product' or something as close to that
which I can manage.  I can always go back and rescan film, if necessary,
but I can't recreate my original digital camera images.   Perhaps I
should always save the original files, but that would require quite a
lot of duplication, so I don't want to do that if it is not necessary.

The calibrat ion/profiling I did for my old CRT monitor seemed to stay
within a relatively narrow range, and dispcal -r gave mea gamma values
consistent with other measures.   It may be that I just have to get a
better monitor which is easier to profile using argyllcms, but I would
rather put that off until the economy, and my financial situation, as a
retiree, improve..
> 
> Does this <http://www.argyllcms.com/doc/gamma.html> help at all ?
> 
> Graeme Gill.

dispcal -v -yl -qh -t6000 -b125 -g2.2 -o TargetX

LCD settings
B 35 C 53
R 39  G 53 B 42
Gamma setting 3

.....
.....
Adjust CRT brightness to get target level. Press space when done.
   Target 0.84
/ Current 0.83  + 

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit
Doing some initial measurements
White = XYZ 121.50 126.13 132.79

Adjust CRT Contrast or LCD Brightness to get target level. Press space when 
done.
   Target 125.00
/ Current 126.14  - 

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit
Doing some initial measurements
Red   = XYZ  60.77  29.59   3.53
Green = XYZ  23.86  67.67  15.52
Blue  = XYZ  16.47   7.69  84.76
White = XYZ 121.46 126.07 132.82

Adjust R,G & B gain to get target x,y. Press space when done.
   Target Br 125.00, x 0.3217, y 0.3377
/ Current Br 128.85, x 0.3181, y 0.3350  DE  1.9  R++ G+  B-    

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit
Doing some initial measurements
Black = XYZ   0.51   0.48   0.65
Grey  = XYZ  27.09  27.24  27.61
White = XYZ 122.27 128.77 133.38

Adjust CRT brightness to get target level. Press space when done.
   Target 1.29
/ Current 1.06  + 

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit
Doing some initial measurements
White = XYZ 122.22 128.72 133.34

Adjust CRT Contrast or LCD Brightness to get target level. Press space when 
done.
   Target 125.00
\ Current 128.75  - 

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit
Doing some initial measurements
White = XYZ 122.22 128.71 133.31

Adjust R,G & B gain to get target x,y. Press space when done.
   Target Br 125.00, x 0.3217, y 0.3377
\ Current Br 124.03, x 0.3209, y 0.3293  DE  5.8  R-  G++ B-   

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit
Doing some initial measurements
White = XYZ 120.86 124.03 131.80

Adjust CRT Contrast or LCD Brightness to get target level. Press space when 
done.
   Target 125.00
\ Current 124.00  + 

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit
Doing some initial measurements
Black = XYZ   0.50   0.48   0.65
Grey  = XYZ  26.83  26.59  27.23
White = XYZ 120.82 123.94 131.74

Adjust CRT brightness to get target level. Press space when done.
   Target 1.24
\ Current 1.04  +  

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit
Doing some initial measurements
White = XYZ 120.84 123.98 131.72

Adjust CRT Contrast or LCD Brightness to get target level. Press space when 
done.
   Target 125.00
\ Current 113.59  + 

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit
Doing some initial measurements
Black = XYZ   0.53   0.49   0.67
Grey  = XYZ  25.03  24.86  25.91
White = XYZ 111.07 113.43 118.79

Adjust CRT brightness to get target level. Press space when done.
   Target 1.13
\ Current 1.04  + 

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit
Doing some initial measurements
White = XYZ 127.51 131.18 136.71

Adjust CRT Contrast or LCD Brightness to get target level. Press space when 
done.
   Target 125.00
\ Current 94.78  + 

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit
Doing some initial measurements
Black = XYZ   0.48   0.45   0.62
Grey  = XYZ  21.69  21.72  22.57
White = XYZ  93.58  94.68  97.56

Adjust CRT brightness to get target level. Press space when done.
   Target 0.95
\ Current 0.93  + 

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit
Doing some initial measurements
White = XYZ 130.42 134.66 139.37

Adjust CRT Contrast or LCD Brightness to get target level. Press space when 
done.
   Target 125.00
/ Current 124.46  + 

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit
Doing some initial measurements
Black = XYZ   0.50   0.46   0.59
Grey  = XYZ  25.08  24.87  25.20
White = XYZ 119.79 123.87 127.69

Adjust CRT brightness to get target level. Press space when done.
   Target 1.24
/ Current 1.22  + 

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit
Doing check measurements
Black = XYZ   0.44   0.41   0.55
Grey  = XYZ  24.99  24.78  25.10
White = XYZ 119.45 123.49 127.35
1%    = XYZ   1.21   1.19   1.24

  Target Brightness = 125.00, Current = 123.49, error = -1.2%
  Target 50% Level  = 26.88, Current = 24.78, error = -1.7%
  Target Near Black =  1.23, Current =  1.25, error =  0.0%
  Target white = x 0.3217, y 0.3377, Current = x 0.3226, y 0.3335, error =  
3.74 DE
  Target black = x 0.3217, y 0.3377, Current = x 0.3329, y 0.3267, error = 
12.37 DE

Press 1 .. 7
1) Black level (CRT: Offset/Brightness)
2) White point (Color temperature, R,G,B, Gain/Contrast)
3) White level (CRT: Gain/Contrast, LCD: Brightness/Backlight)
4) Black point (R,G,B, Offset/Brightness)
5) Check all
6) Measure and set ambient for viewing condition adjustment
7) Continue on to calibration
8) Exit
Commencing device calibration
patch 6 of 6
Black = XYZ   0.44   0.40   0.55
Red   = XYZ  55.87  27.21   3.15
Green = XYZ  22.56  64.07  14.40
Blue  = XYZ  15.51   7.35  79.82
White = XYZ 119.20 123.26 127.07
patch 160 of 160
Had to scale brightness from 125.000000 to 121.658451 to fit within gamut,
corresponding to RGB 0.973363 1.000000 0.974791
Target white value is XYZ 115.896447 121.658451 122.717970
Adjusted target black XYZ 0.42 0.38 0.54, Lab 2.85 1.68 -1.99
Target black after min adjust: XYZ 0.42 0.38 0.54, Lab 2.85 1.68 -1.99
Gamma curve input offset = 0.107259, output offset = 0.000000, power = 2.579110
~1 t1 = 1.000000, t0 = 0.003158
~1 a1 = 0.998691, a0 = -0.005332
~1 vn1 = 0.992847, vn0 = 0.008452
~1 fix a1 = 1.000000, should be = 1.000000
~1 fix a0 = 0.003158, should be = 0.003158
Viewing conditions adjustment aprox. power = 1.247074
Total Iteration 4, Final Samples = 96 Final Repeat threshold = 0.400000
Creating initial calibration curves...
Doing iteration 1 with 12 sample points and repeat threshold of 1.131371 DE
patch 12 of 12
Brightness error = -4.368468 cd/m^2
White point error = 0.528367 deltaE
Maximum neutral error (@ 1.000000) = 1.499187 deltaE
Average neutral error = 0.711628 deltaE
Failed to meet target 1.131371 delta E, got worst case 1.499187
Number of measurements taken = 46
Computing update to calibration curves...
Doing iteration 2 with 24 sample points and repeat threshold of 0.800000 DE
patch 24 of 24
Brightness error = -3.326765 cd/m^2
White point error = 0.844937 deltaE
Maximum neutral error (@ 1.000000) = 1.356323 deltaE
Average neutral error = 0.517080 deltaE
Failed to meet target 0.800000 delta E, got worst case 1.499187
Number of measurements taken = 58
Computing update to calibration curves...
Doing iteration 3 with 48 sample points and repeat threshold of 0.565685 DE
patch 48 of 48
Brightness error = -3.478413 cd/m^2
White point error = 0.828954 deltaE
Maximum neutral error (@ 1.000000) = 1.385647 deltaE
Average neutral error = 0.387713 deltaE
Failed to meet target 0.565685 delta E, got worst case 1.499187
Number of measurements taken = 173
Computing update to calibration curves...
Doing iteration 4 with 96 sample points and repeat threshold of 0.400000 DE
patch 96 of 96
Brightness error = -3.665476 cd/m^2
White point error = 0.859979 deltaE
Maximum neutral error (@ 1.000000) = 1.452488 deltaE
Average neutral error = 0.347785 deltaE
Failed to meet target 0.400000 delta E, got worst case 1.499187
Number of measurements taken = 711
The instrument can be removed from the screen.
Written calibration file 'TargetX.cal'
Luminance XYZ = 0.000000 122.063836 0.000000
White point XYZ = 0.953280 1.000000 0.964425
Black point XYZ = 0.003146 0.002712 0.004456
Created fast shaper/matrix profile 'TargetX.icc'
[len@localhost ~]$ dispwin -I TargetX.icc
[len@localhost ~]$

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