[argyllcms] Re: Calibrating problems in darks areas

  • From: lee scratchy <leescratchy@xxxxxxxxxxx>
  • To: <argyllcms@xxxxxxxxxxxxx>
  • Date: Fri, 28 Dec 2007 20:59:50 +0000

yeah it does have RGB levels options, just set the color temperature to USER, 
then you can play with BLUE and RED levels.

well did you try my banding test patterns ?
show me yours that exhibit the problem

well yeah D65 has a slightly redish white point, it's the reference

> From: frederic.mantegazza@xxxxxxxxxxx
> To: argyllcms@xxxxxxxxxxxxx
> Subject: [argyllcms] Re: Calibrating problems in darks areas
> Date: Fri, 28 Dec 2007 21:39:29 +0100
> 
> On jeudi 27 décembre 2007, lee scratchy wrote:
> 
> > "dispcal -v -yc -t6500 -gl -qh test"
> >
> > and really work on the precalibration options from 1>4 ;)
> 
> Ok, here are the results (see below). As the A901HT don't have RGB offset 
> adjustement, I can't get a very good black point. And I still have banding 
> effects...
> 
> And with this adjustement, white seems to have a red color cast. Is it 
> another hardware problem?
> 
> $ dispcal -v -d 2,1 -y c -t6500 -gl -qh A901HT
> Setting up the instrument
> Place instrument on test window.
> Hit Esc, ^C or Q to give up, any other key to continue:
> Display type is CRT
> Target white = 6500.000000 degrees kelvin Daylight spectrum
> Target brightness = native brightness
> Target gamma = L* curve
> 
> Display adjustment menu:
> 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 some initial measurements
> 
> Adjust CRT brightness to get target level. Press space when done.
>    Target 1.14
> \ Current 1.16  -
> 
> 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 some initial measurements
> 
> Adjust R,G & B gain to get target x,y. Press space when done.
>    Target B 112.09, x 0.3128, y 0.3291
> \ Current B 109.74, x 0.3131, y 0.3300  DE  0.6  R-  G-- B+
> 
> 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 some initial measurements
> 
> Adjust CRT Contrast or LCD Brightness to desired level. Press space when 
> done.
>   Initial 109.66
> \ Current 109.74
> 
> 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 some initial measurements
> 
> Adjust R,G & B offsets to get target x,y. Press space when done.
>    Target B 1.10, x 0.3128, y 0.3291
> / Current B 1.40, x 0.2809, y 0.3575  DE 22.0  R+  G-- B+
> 
> 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   0.39   0.44   0.56
> Red   = XYZ  51.60  27.75   2.90
> Green = XYZ  36.51  76.75  13.52
> Blue  = XYZ  20.95  10.65 109.08
> White = XYZ 104.16 109.82 118.94
> patch 80 of 80
> Initial native brightness target = 109.821478 cd/m^2
> Had to scale brightness from 109.821478 to 109.155734 to fit within gamut
> Target white value is XYZ 103.750160 109.155734 118.804211
> Adjusted target black XYZ 0.42 0.44 0.48, Lab 3.64 0.00 0.00
> Target black after min adjust: XYZ 0.49 0.52 0.56, Lab 4.29 0.00 0.00
> Current gamma curve offset = 0.137862, Gamma curve power = 2.703782
> Total Iteration 4, Final Samples = 96 Final Repeat threshold = 0.500000
> Creating initial calibration curves...
> Doing iteration 1 with 12 sample points and repeat threshold of 4.000000 DE
> patch 12 of 12
> Brightness error = -1.057560 cd/m^2
> White point error = 0.105273 deltaE
> Maximum neutral error (@ 0.242624) = 1.764902 deltaE
> Average neutral error = 0.925211 deltaE
> Computing update to calibration curves...
> Doing iteration 2 with 24 sample points and repeat threshold of 2.000000 DE
> patch 24 of 24
> Brightness error = -1.449498 cd/m^2
> White point error = 0.662965 deltaE
> Maximum neutral error (@ 0.057750) = 1.425828 deltaE
> Average neutral error = 0.871021 deltaE
> Computing update to calibration curves...
> Doing iteration 3 with 48 sample points and repeat threshold of 1.000000 DE
> patch 48 of 48
> Brightness error = 1.133949 cd/m^2
> White point error = 0.548879 deltaE
> Maximum neutral error (@ 0.688472) = 0.998333 deltaE
> Average neutral error = 0.590139 deltaE
> Computing update to calibration curves...
> Doing iteration 4 with 96 sample points and repeat threshold of 0.500000 DE
> patch 96 of 96
> Brightness error = -0.348474 cd/m^2
> White point error = 0.464447 deltaE
> Maximum neutral error (@ 0.362283) = 0.538733 deltaE
> Average neutral error = 0.345814 deltaE
> 
> $ profile -v -A "901HT" -q h -a l -d mt -T p A901HT
> No of test patches = 2000
> Estimating white point
> Approximate White point XYZ = 0.956397 1.003184 1.103095, Lab = 
> 100.122986 -1.882631 -20.131584
> Creating optimised per channel curves
> About to optimise temporary matrix
> ..................
> About to optimise input curves and matrix
> ...........................................
> About to optimise output curves and matrix
> ............................................
> About to optimise input curves and matrix again
> .
> About to optimise input, matrix and output together
> ......................................
> About to adjust a and b output curves for white point
> 
> Creating fast inverse input lookups
> Compensate scattered data for input curves
> Compensate scattered data for output curve
> Create clut from scattered data
> ********************************************
> Find white & black points
> White point XYZ = 0.954914 1.000671 1.099451, Lab = 
> 100.025936 -1.722174 -20.056039
> Black point XYZ = 0.004557 0.004770 0.005234, Lab = 
> 4.308683 -0.171197 -2.452371
> Fixup clut for white point
> Check White point XYZ = 0.954914 1.000671 1.099451, Lab = 
> 100.025938 -1.722174 -20.056039
> Done A to B table creation
> Creating B to A tables
> 100%
> Done B to A tables
> profile check complete, peak err = 3.427144, avg err = 0.645118
> Exectution time = 1116.910000 seconds
> 
> -- 
>    Frédéric
> 
>    http://www.gbiloba.org
> 
> 

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