Home › Forums › Help and Support › How to maintain measured uncalibrated gamma?
- This topic has 6 replies, 2 voices, and was last updated 10 months, 1 week ago by Vincent.
2022-05-13 at 10:08 #35374
If my desire is to maintain screen gamma while using 3Dlut with MPV or DwmLut will it suffice if I hit “as measured – tone” and then pick the “measured uncalibrated display – tone” in the tone curve 3D Lut page alongside toggling “Apply VCGT“?
I suspect that nothing happens if I hit “apply VCGT” without calibrating to the measured gamma as well.2022-05-13 at 18:54 #35378
I suspect that nothing happens if I hit “apply VCGT” without calibrating to the measured gamma as well.
Because the required grey correction will be computed from display profile TRC and the gamma you want to simulate in source colorspace.
Multistage ArgyllCMS calibration (profile VCGT contents) can have more information about native/uncalibrated TRC than TRC from profiling alone. For example a 10 node per cube edge requires 1000 patch set with 10 TRC measurements. VCGT can store a correction up to 10 times that.
In the end the final results depend on how bad is uncalibrated grey color. On a well behaved display with neutral color in greys you can skip TRC calibration and use only profile info.2022-05-14 at 3:27 #35382
I see. It should definitely be done with ill behaved displays, which is pretty much all consumer grade ones, reading some more on the “documentation” page made me understand how important it is to calibrate with the monitor’s actual black point in mind.
I do not quite understand the “simulated TRC+gamma” thing inside the 3D Lut page. Should I go with the option that ignores that if I want to keep the calibrated gamma intact and get what I would also get if I used the icc + the loader in a managed software?2022-05-15 at 10:06 #35399
Shouldn’t including the VCGT parameters in the LUT creation prevent me from needed to load an ICC in conjuction with the LUT file ?
Color managed apps will need an ICC to identify monitor behavior. Once you load a LUT3D in DWMLUT that behavior will/should be the colorspace you chose as “source colorspace”.
You cannot apply a LUT3D on top of a color managed app (or configured to use OS color management settings)… you applied it twice.
It’s like going in circles. If you configure Resolve to use ICC you cannot use LUT3D. If you use LUT3D you cannot apply ICC color correction INSIDE Resolve ( “Use Mac Color profiles for viewers”).
Which is it?2022-05-15 at 12:12 #35401
Both are true.
You apply a LUT3D with DWMLUT, then choose as default display profile what you are simulating. Color managed apps will believe that display behaves as if it was like simulated colorspace.
But you should not do the opposite, apply an ICC that describes actual display behavior for a color managed app that will correct colors inside that app, and then (=”AFTER”) apply a LUT3D that corrects that display on top of color management engine of that app. You’ll be doing it twice.2022-05-15 at 12:28 #35404
Make sense I get it now, thank you!
I think I need to find a way to strip the ICM profile of the corrections and have it solely contain the characterization of my monitor that MPV could use before applying the 3D Lut. I could just use the default empty profile from the OS but ti doesn’t describe the gamma, contrast ratio and other relevant numbers.2022-05-15 at 12:59 #35405
If MPV can use LUT3D, then just change default display profile to the one bundled with display driver (or one from EDID data). That profile should not store VCGT data and when you load it it should clean 1DLUT calibration applied in GPU by your custom ICC profile.
In MS windows with madVR it is not needed since madVR itself cleans 1D LUT in GPU. IDNK if MPV has that feature.