Are gamma values in excess of 10 normal?

[Mark Casazza]

I am running display cal on kunbuntu 22.04 with a datacolor Spyder X. My monitors include a Dell 2007FP and a pair of HP 24uh.I also have a Viewsonic VA1926w attached that I don’t bother to calibrate.

My Dell can only muster a cd/m2 of 78.42, but that is fine. At max brightness I can tune the color to within a DE of 0.3 This was done with the dispcal -d 2 -H -t 6500 -b 120 dummy command. Then I check the gamma with

dispcal -d 2 -v -R

and I get 12.51.

The HP monitors can get much brighter, but I tune them to either 120 or 100 cd/m2. I prefer 100. At 120 cd/m2 I get a gamma of 17.23.  At 100 cd/m2 the gamma was 19.07.

I understand that when operating in a dim environment higher gamma values are acceptable, but these seem crazy. I am trying to follow the calibration workflow described at https://rawtherapee.com/mirror/dcamprof/argyll-display.html. This workflow suggests using the monitor’s gamma in the calibration process, but with it being so far from 2.2 I am not sure the best way to proceed. I am looking for advise.

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[Vincent]

These uncalibrated values are to high for a new LED display like those HP. Check if there is some software running liek GPU controls or if that SPyder X is not broken (measure a known well behaved display, or at least one that looks like 2.2/2.4)

[Mark Casazza]

It may be the Spyder X. I pulled an old Spyder 3 out of the closet and redid the process. This got me a Approx Gamma of 2.3. That is much better.

Oddly enough the Spyder X seesm to work fin in Windows on the same computer. Go figure.

Marl

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