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Hi Florian,
Please see the pictures attached. After calibration and profiling (this is madVR) I see this strange artefacts when high level red is displayed on screen. Pictures show with and without calibration applied.
I had that before with blue but it was only noticeable very seldom, not happening on my monitor so I didn’t bother you! But now it’s pretty severe.
What could that be? Do you require the calibration package?
Thanks
Tony
Attach the profile please (in DisplayCAL “Create compressed archive…” next to settings, do not include 3D LUT files).
That profile has some bad clipping. I’m not sure if that’s due to the weird display response (which shows signs of the red channel clipping), but try regenerating the profile using this development build of ArgyllCMS:
(menu “File” -> “Locate ArgyllCMS executables”, then “Create profile from measurement data…”).
Btw, (unrelated) you used black point hue correction during calibration. Not sure if that was intended, because it means you’re sacrificing contrast.
It was intended – I went through the documentation and I thought it was a good idea to have a little correction. I thought it was correcting the grey close to black, not the black itself. I’ll keep that in mind, maybe I’ll re-do the calibration without it.
I can check the clipping with an uncorrected chart before calibration. Maybe I can play with the contrast control and improve it before I run the calibration?
I’ll do what you suggest and report back. Thanks for your help!
I thought it was correcting the grey close to black, not the black itself.
Gray close to black is always corrected to some extent, and the rate of blend over to the native blackpoint can be controlled with the “Rate” control (but there is little need to change this from the default of “4”).
Hi Florian,
The outcome with the beta Argyll is massively better but still clipped.
I am also attaching some screenshots of the colour clipping charts, no 3dlut, old 3dlut, new 3dlut.
I have played with the projector controls with no 3dlut and I can’t seem to be able to improve the situation.
Any advice appreciated. Thanks
… and the final picture (ran out of available attachment).
Also, thank you for your advice on the black point correction.
The projector unfortunately only has around 81% Rec 709 coverage, which is not great. Another problem is that the red and blue channel are already clipping without 3D LUT, so this needs to be addressed. Either use RGB gains or saturation controls until you can see at least up to and including level 235 in all three channels.
To take the low Rec 709 coverage into account, create a 3D LUT that compresses rather than clips by setting rendering intent to perceptual.
I know the projector is not the best and its gamut is limited. Well, it has a “cinema” mode which slides in an extra filter (mechanically) and the gamut becomes perfect – but eating up HALF of the light!
I will try again but I am unable to avoid that clipping apparently. I have played with all the available controls (Contrast, brightness, gamma, gain, colour temp, picture mode) and still I cannot display RGB – but I can see white not being clipped? Next I’ll try is to change the HDMI level (both on PC and projector) to see if that is better handled.
Thanks for the hint on the compressed 3DLUT.
