Inverse tone curve for better HDR "Effect" - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 2 Old 03-06-2020, 06:48 AM - Thread Starter
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Inverse tone curve for better HDR "Effect"

So Philips seems to have the best SDR-to-HDR upconversion in OLEDs, followed by Sony, and LG's HDR Effect, on C9 at least, can be a hit or a miss. After much back and forth with SDR with max OLED light and a toned down HDR Effect so that it presents all details in the SDR container, HDR Effect does seem to push highlights more than SDR at max (100 OLED light and Peak Brightness to High), but the mids also rise substantially like the max SDR one, even if not the same amount (mild inverse tone mapping at best), making high-key content too bright, along with some other quirks such as revealing more artifacts in the dark areas of low bandwidth content and grey bars if played via USB.

Anyhoo, after being unhappy with that and accurate SDR modes pushed to max light being too bright in mids, I thought of trying out 22 points white balance to tweak the gamma curve in the maxed out SDR mode. With gamma at 2.4, I raised the target luminance to 500, and then these IRE values:

100: +50
95: +35
90: +20
85: +10
80: 0
75: -10
70: -20
65: -25
60: -25
55:-25
50: -20
45: -15
40: -12
35: -9
30: -6
25: -3

Rest unchanged.

Idea was to only push up the areas that won't be on skin, except some highlights, and bring down the mids, and leave the dark areas as they were, especially as raising OLED light to 100 and peak brightness to max makes the whiter skins shine too much.

Works better than HDR effect. Going back and forth with another mode set up with matching max settings but default white balance, and then using the greyscale pattern, the effect is easy to notice; whites go higher and mids go down. High-key shows are more comfortable to watch. Outdoor shots gain a lot more oomph and skin tones are closer to accurate SDR modes with lower brightness. Dark areas remain unchanged basically without any side effects.
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post #2 of 2 Old 03-06-2020, 09:06 PM - Thread Starter
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Refined this more. Instead of using random values and bringing down where I thought it should, I calculated values for 2.6 gamma and adjusted the values to that. Then I tried to 2.8 and then 3.2. Now I'm using 3.2 till 45 IRE and then tapering off till 15 IRE to 2.4.
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hdreffect , lgc9 , oled

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