[argyllcms] Re: Multiple issues with Argyll, please help

  • From: Rajiv Mehra <to_rajivmehra@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sat, 23 Aug 2008 09:19:18 -0700 (PDT)

Ok, today I cannot even run dispcal to completion. I added the -f1 -k0 as was 
suggested.
Now it gets stuck at patch 25 (a dull red) every time I run it. It gives me an 
option to retry but when I press any key, it just exits.
How do I proceed?
This is the full output :

C:\calibration\Argyll_V1.0.2\bin>dispcal -v -y c -q m -w 0.313,0.329 -g 709 -p 
0.5,0.5,1.7 -f1 -k0 g70-1
Setting up the instrument
Place instrument on test window.
Hit Esc, ^C or Q to give up, any other key to cont
inue:
Display type is CRT
Target white = xy 0.313000 0.329000
Target white brightness = native brightness
Target black brightness = native brightness
Target gamma = REC 709 curve
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
Commencing device calibration
patch 6 of 6
Black = XYZ   0.00   0.00   0.00
Red   = XYZ  14.90   7.70  -0.12
Green = XYZ  13.27  25.93   4.15
Blue  = XYZ   4.89   2.17  27.18
White = XYZ  33.06  35.81  31.06
patch 25 of 64
Sample read failed due to communication problem.
Hit Esc, ^C or Q to give up, any other key to retry:
The instrument can be removed from the screen.
dispcal: Error - display read failed with 'Instrument Access Failed'

C:\calibration\Argyll_V1.0.2\bin>

 Regards,
Rajiv Mehra



----- Original Message ----
From: Florian Höch <lists+argyllcms@xxxxxxxxx>
To: argyllcms@xxxxxxxxxxxxx
Sent: Tuesday, August 19, 2008 12:25:58 PM
Subject: [argyllcms] Re: Multiple issues with Argyll, please help

Hello,

> 1. On my G70, with Argyll's calibration the image's black level is 
> raised......all blacks are now grey-ish. I get much better shadow detail now 
> but no true black. This defeats the purpose of having a CRT projector. Is 
> there a way to tell Argyll not to raise the black level? 
> 
> 2. The results for low IREs are not good, they are very greenish. 
> This may be a meter limitation but does Argyll take multiple readings at low 
> IREs and average them out?
> Is there a way to manually change the .cal file?

maybe try the -f1 and -k0 options of dispcal. -f1 should help with the 
"gray blacks". Alernatively try using the -a option or measure ambient 
light when calibrating (if you have for example a i1 Display 2, which 
allows this). -k0 will not try to correct black point hue, which might 
eliminate the green cast.

> 3. Only while calibrating my CRT projector and only while using the -F option 
> (which makes the background black) dispcal gets stuck at a red patch, I think 
> it is patch #25 or something. The error is "no data from sensor" or something 
> similar. Hence I am never able to run dispcal to completion when using the -F 
> option. That -F option is very important for my CRT PJ.
> 
> Strangely, the -F works fine on all other displays like LCD or plasma.

Most instruments have problems measuring very dark patches on devices 
that produce very low black levels (I have an old CRT here that measures 
a contrast ratio of about 1100:1 if the measurement window is surrounded 
with a gray background and when I try to measure an absolute black 
screen, the reading usually fails - I have an i1 Display Clorimeter). 
But you said it is a red patch? This seems strange.

> 4. On my plasma TV the green primary is way off. It is much more saturated 
> than reference. 
> I was hoping that Argyll, being a CMS, will correct it......it does not. 
> What's up? I am doing something wrong? 

Are you using just dispcal? With it alone you cannot correct this (just 
neutrals, tone curve, white and blackpoint). You need to use colprof in 
addition to create a profile, and use that with a color mangement aware 
application that can actually use the profile. Also, what do you refer 
to when you mention "reference"?

> 5. If running dispcal and option 2, I check the whitepoint color 
> temp.......Argyll reports that my patch is way off. It tells me to increase 
> the red. With HCFR (another calibration metering software) I can see that the 
> whitepoint is spot on! Even my eyes can tell that it is nearly perfect. Why 
> does Argyll think that the readings are not close to 6500?

What is the reported color temp and dE to the locus?

Regards,

Florian Höch

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