Originally Posted by BigCoolJesus
Finally decided to calibrate my LG OLED C6 for HDR10 playback using the CalMAN workflow and Masciola's patterns on an USB stick. Not going to jump into UHD/HDR too much, but my Xbox One S is finally connected to an HDR capable receiver and a few games I have support HDR (like Mass Effect Andromeda), so figured I should at least get the settings in line.
From my understanding, pretty much the only thing I can/should measure and change, using the HDR Standard picture mode, is the the Brightness, OLED Light, Contrast, Color (Tint) and the Gamma adjustments. Correct?
Also, is the ST 2084 HDR (PQ) Gamma curve the only curve one should use for HDR10 calibration or can the traditional power values (such as 2.2, 2.3, 2.4, etc) be used? I'm a little confused by the EOTF curve graph in place of the traditional Gamma curve graph for CalMAN...
Hi, Contrast/Brightness settings in HDR are not working like we know in SDR, Brightness should left untouched, because the display gamut/tone mapping is based to these default settings.
HDR is using ST.2084 which is an absolute curve, the display has to follow specific luminance levels per digital level, according to the Dolby's golden reference numbers, so you are following to up to the luminance levels the display is capable and you clipp or roll-off (hard/soft)...(it's up to each display internal gamut/tone mapping programming)...the higher from display's peak output levels the display can't follow.
So when you have a 650nits capable display you see about up to 70.5% of the signal, the other info will be clipped or roll-off (hard/soft), it's up to each display internal gamut/tone mapping programming.
75.2% is 1000 nits
90.2% is 4014 nits
97.7% is 8047 nits
100% is 10000 nits
The PQ curve charts have different curve shape from the familiar ones of SDR calibration because 100% is 10.000 nits.
If you reduce Contrast/OLED from LG, you will reduce the peak output, OLED/Contrast @ 100 provides better color tracking at these default values.
In SDR we use Gamma curve as transfer function (where you can set it to 2.2/2.4/BT1886 or whatever value you like....having in calculation the display Black/Peak White level to generate each digital level luminance levels, but in HDR the PQ Curve transfer function has fixed numbers from 0-10.000nits, you follow or you clip, you can't modify or use other values.
Ignore CMS adjustments and do RGB Balance adjustments only.
Each of the White Balance control in HDR has a specific +- value working range which not introduce problems to real content. The range of values are different from point-to-point. At low end controls the adjustments has to be very minimal. Play some different content and play with each control until you find up to which values you don't see problems. Use different movies/scenes to have plenty of different palettes to evaluate.
Using LG instructions for HDR calibration it will increase your color errors and provide lower peak output but better Grayscale and gamma tracking, but the color errors are more important from grayscale errors in that case.
After some testing performed using a 65E6 @ HDR mode, lowering the OLED Light, can improve the Grayscale but increase the color errors. To compare what is happening you have to take 5-Point Saturations (or 10-Point)
If you keep the Contrast/OLED @ 100, and calibrated the RGB levels for HDR, then you get an average Grayscale of about 1.6dE2000 and the errors are coming from gamma (brigher) at mid range while the RGB balance is near perfect....you get about 670nits calibrated.
If you run a 5-Point Saturation with targets DCI P3 inside a REC2020 (look CalMAN HDR workflow) then you get about ~2.0dE2000
If you keep the Contrast @ 100 and reduce OLED about 80? (I don't remember the exact value...to get 540nits) and calibrated the RGB levels for HDR, then you get an average Grayscale of about ~1.0dE2000 (or lower)and the errors of gamma are reduced at mid range while the RGB balance is near perfect....you get about 540nits calibrated.
If you run a 5-Point Saturation with targets DCI P3 inside a REC2020 (look CalMAN HDR workflow) then you get about ~4.0dE2000