[argyllcms] dispcal VDT DE 2K measurement discrepancy

  • From: Vallo Kallaste <kalts@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Mon, 15 Dec 2014 22:22:08 +0200

Hi

I noticed that dispcal VDT DE 2K measurements are always off by small amount.
By the measurements I mean those in the interactive display adjustment menu:
5) Check all
2) White point (Color temperature, R,G,B, Gain/Contrast)

I would like to know which one is right.

/--/
$ dispcal -v2 -P 0.8,0.5,2 warmup
Setting up the instrument
Instrument Type:   ColorMunki
Serial Number:     xxxxxxx
Firmware version:  288
Chip ID:           01-00CF7011000039
Version string:    'colormunki FW V1.32  Build Nr. 1303'
Calibration Ver.:  6
Production No.:    33111
Set instrument sensor to calibration position,
 and then hit any key to continue,
 or hit Esc or Q to abort: 
Calibration complete

Place instrument on test window.
Hit Esc or Q to give up, any other key to continue:
Target white = native white point
Target white brightness = native brightness
Target black brightness = native brightness
Target advertised gamma = 2.400000

Display adjustment menu:
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
Measured display update delay of 8 msec, using delay of 112 msec
Black = XYZ 0.1179 0.1281 0.1718
Grey  = XYZ 24.530 26.368 26.061
White = XYZ 101.302 106.492 102.615
1%    = XYZ  0.870  0.908  0.948

  Current Brightness = 106.49
  Target 50% Level  = 20.176, Current = 26.368, error =  5.8%
  Target Near Black = 1.0649, Current = 0.9842, error = -0.1%
  Current white = x 0.3263, y 0.3431, VDT 5750K DE 2K  0.8
  Target black = x 0.3263, y 0.3431, Current = x 0.3190, y 0.3331, error =  
5.06 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
Doing some initial measurements
Red   = XYZ 62.903 29.060  0.883
Green = XYZ 21.043 70.503 10.612
Blue  = XYZ 17.502  6.793 91.432
White = XYZ 101.000 105.884 102.592

Adjust R,G & B gain to desired white point. Press space when done.
  Initial Br 105.88, x 0.3264 , y 0.3421 , VDT 5769K DE 2K  0.1
/ Current Br 105.84, x 0.3263+, y 0.3421-  VDT 5770K DE 2K  0.1  R=  G=  B=  q
Sample read stopped at user request!
Hit Esc or Q to give up, any other key to retry:
The instrument can be removed from the screen.
dispcal: Error - display read failed with 'User Aborted'

/--/

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