Originally Posted by madshi
4K HDR to SDR Madvr Implementation
I am a very happy user of Madvr, especially for 4K Upscaling of my favorite bluray via NGU.
Thank you so much!
I have been recently also using your HDR to SDR (DCI-P3) shader math implementation with my projector Epson EH-LS10000 which can be perfectly calibrated to DCI-P3 D65.
I started using 400nits as "this display's peak nits" and it looked very nice.
However, I also noticed that for some portion of the HDR videos, the avg frame HDR peak luminance measured by Madvr (seen with Ctrl+Y) was lower than that. Sometimes, it even gets lower that 120nits for a longer period of time.
I created some keyboard combination shortcuts to quickly be able to change from 120nits to 1000nits.
As I result, I can clearly see that the user would get better brightness and HDR quality, if the display peak nits could be dynamicly based on what peak luminance madvr measure.
Could you implement something like this?
- use display peak nits as long as maximum frame peak luminance does not get below.
- if peak luminance get below, use peak luminance as new "display's peak nit"
Or something even smarter that you could come up with. I think there is much more to be gained from Madvr analysing each frame luminance as what is currently implemented. (maybe something based on the area of a luminance above a certain level...)
Again about HDR implementation and HDR to SDR implementation in Madvr.
Sony has used a pretty smart implementation of the ST2084 HDR Curve on it's 4K HDR projector (Sony VW520ES and Sony VW550ES).
This french review explains it very well.
Basically, Sony used a multiplicator on the ST2084 HDR to have a nice viewing experience on display like projector which will have at MAXIMUM 100nits true peak brightness. From what Alex_t is saying, this is very similar to the "Dolby Cinema" implementation of HDR.
- ST2084 at 400nits is about what Sony used for the Sony VW550ES which result in a multiplication factor of 4 if the projector outputs real 100nits peak brightness.
- ST2084 at 480nits is about what Sony used for the Sony VW520ES which result in a multiplication factor of 6 if the projector outputs real 80nits peak brightness.
Could you give us this option of using a multiplicator for the HDR curve? This would be very usefull for all of projector user.
For HDR to SDR, I imagine the process could be:
- take original ST2084 curve
- Apply multiplicator
- Translate to SDR Gamma 2.2 (for example) as you already do.
4) Again, thank you for your hard work on your free time. Madvr is a wonderful tool. I hope you can bring those ideas to real life. This would certainly be a huge improvement for all projector users with low nits (<100nits) output.