Comment by Negitivefrags | Hacker News Reader

Comment by Negitivefrags | Hacker News Reader

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With regard to HDR for display, I tried quite a while to be able to reproduce a situation where HDR had any benefits in a real time rendering context.

The only case I could really find where it makes a difference is in slow and smooth colour gradients on which you can see the increased precision. However, that can also be basically solved by adding (rand()-0.5)/255 to all fragments before output.

The increased brightness kind of doesn't matter since SDR content is usually just stretched to fill the increased brightness range.

The most interesting thing for me was the wider colour gamut that you get with the rec2020 colour primaries. Unfortunately I couldn't really reproduce anything looking actually different, let alone better.

I was doing my lighting in the rec2020 colour space, and I was producing out-of-gamut colours for rec709, so I really was seeing colours that SDR content would be totally unable to produce. Yet somehow my eye just couldn't preceive a difference when switching back and forth between the two images.

I am using an LG OLED which are supposed to be good for HDR so the display shouldn't be the issue.

I would be keen to see some references that really quantify the difference between HDR and non-HDR rendering where the HDR version doesn't just look darker.

What? If it's working, it shouldn't be remotely subtle. Direct light sources and directional single bounces (specular highlights, reflections) benefit enormously from the extra resolution / dynamic range. Metal, water, and damp materials look so much better with HDR than with try-hard gamma-stretched SDR that I would probably even trade away 120fps if I had to. I'm easily willing to spend time restarting into Windows (and tolerating its updates and pushy spamminess) just so that I can game and watch videos in HDR.

Is your computer outputting in 10 bit color to your display? Is it set to the proper range so it will actually display HDR and is your monitor HDR? Just because it is an OLED does not mean the whole chain is working and you are getting true HDR. The difference is pretty night and day for me - I would say a bigger improvement than going from 1080P to 4K personally.

As for wider color gamuts part of the reason they are better is that they have more graduations so you will always have smooth gardients instead of stepped gradients. But the other big thing is that you need 10+ bit color for most codecs to properly record more than 14 stops of light from a camera (which many can do these days). It seems counterintuitive in that color and dynamic range should be totally separate but the way that the codecs work mean that when you are stuck at 8bit color you will not get more than about 13 total stops of DR (which is also the reason we use Log curves - basically to cram more visible DR into the limited range)

> The increased brightness kind of doesn't matter since SDR content is usually just stretched to fill the increased brightness range.

That seems wrong, or at least somewhat disconcerting if true?

But generally the benefit of HDR is retaining details both in highlights and shadows, instead of being blown out/crushed like in SDR.

Yeah. Lost Coast was 15 years ago -- the industry tried to do good HDR without display support for a decade, and then the HDR displays came out and made their best attempts look rubbish by comparison.

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