Error "Window access failed"

[eule40040 SourceForge]

I successfully used Calibration and Characterization after installing dispcalGUI and Argyll CMS into Windows 8.1 following Florian Hoechs advice on fotovideotec.de
Upgrading to Windows 10 did not make any difference apart from the necessity to reinstall the Argyll CMS driver.
Since Windows 10 did not fulfill its promises, I reverted to Windows 8.1, but then eventually back to Windows 10.
Again I reistalled the Argyll CMS driver as explained and followed all of Florian Hoechs advices. But starting Calibration and Characterization produces “Error – display read failed with “Window access failed”. De- and reinstalling of dispcalGUI did not solve the problem. Did anybody experience the same problem ? Could perhaps Florian Hoech give any support ?

[Florian Höch]

Hi, the error message (“Window access failed”) means Argyll CMS was not able to create the test window where the color patches are to be displayed. Some things to check:

• Is the graphics driver up to date?
• Is the desktop set to “True Color” (24 or 32 bit color depth)? (Advanced display properties in Windows)

More information may be available via the logs. Enable “Argyll CMS diagnostic output” in the “Options” menu and start a calibration/profile. Then save a log from the “Tools” menu (“Show log”) and attach it. Thanks.

[Benedict Heinzl]

Hi
I got a similar error but I’m using Resolve as pattern generator.

Tried it on my mac as well. there I get another error. not my day.

Log with the window access error attached. as well as the mac error. (other thing i guess)

Attachments:

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[Florian Höch]

Log with the window access error attached

Does this window access error only happen when using Resolve as pattern generator? From the logs I can see that it fails to set the video card gamma ramps, so this should happen as well if you select “DISPLAY1 @ 0, 0, width 1280, height 800” as display device, and in that case it is probably a video driver issue. What kind of video card and drivers are you using under Windows?

[Benedict Heinzl]

Yes same issue when I use the direct display.
Using resolve as pattern generator.
Meanwhile I tried it with a Virtual Box running Windows 10. Same issue.
Before I used Win 8.1

[Florian Höch]

Try updating your graphics card driver.

[Benedict Heinzl]

Tried it on different systems. One is a virtual machine and one is an old laptop without new drivers…

[Florian Höch]

Virtual machines don’t virtualize video card gamma table hardware. And in the other case (actual machine, but broken drivers) you’re out of luck, unfortunately – video card gamma table access will only work with correctly functioning drivers.

[Benedict Heinzl]

But why does the virtual machine even need to do that? I only run dispcal in it and have resolve as pattern generator. From my understanding it shouldn’t need to access the vcgt in that case.

[Florian Höch]

I only run dispcal in it and have resolve as pattern generator.

Argyll doesn’t have direct support for Resolve, so the test window on the main display is created regardless.

[Benedict Heinzl]

So there is no way of running dispcal in a virtual machine?
When I use the “web” pattern generator it works, but it won’t work for my system. (need the output via Resolve)

Seems I got a bad week with it. Three problems in two days.

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