Originally Posted by Anderegg
Unfortunately, in HDR, your backlight is set to 100% maximum brightness...XDR overdrives the peak luminance, so even with local dimming, the brighter your bright parts of the screen are, the brighter the adjacent ZERO BLACK LEVEL areas will be, simply from blooming bleedover. The black level on the X900F in HDR without local dimming active is around 0.150cd/m...which is far above the 0.04cd/m of SDR calibrated to 100cd/m.
If you set XDR to high, it will ramp up and make brighter the 50-70% luminance range, which would have a similar "to the eye" effect of raising gamma...those below peak luminance areas would get brighter, so people would think the HDR looks brighter. As many know, increasing gamma may make a picture look brighter, but it's messing with a curve, not actually increasing peak brightness, which is what you're after in HDR highlights.
It's difficult to 100% test HDR with features such as local dimming and XDR, as you can really only half trust the readings due to the dynamic nature of the function, and the fixed nature of the 10% target box system of taking measurements mixed with the dynamic nature of ABL auto backlight limiter, which will drop brightness after a second or so to decrease power consumption. That last part is explained better in rtings for brightness figures.
So,in your opinion, what are the best XDR and ALD settings with HDR?
In SDR i have ALD to medium/high without problems.
Between ALD medium and high which is better in your opinion?
You have told before that XDR has the 'eye effect' of increase gamma...so,it would make sense decrease the gamma value of the tv with HDR?
For example set gamma -1.
Or, alternatively,turn completely off XDR with HDR content?
Or turn down a little bit the brightness of the tv.
It could be interesting to find a good compromise between an SDR and HDR image,for have a more bright abd vibrant image but not maximum bright values for have better black levels..