Comment by mrandish
2 days ago
> I think the solution for HDR is similar penalization based on log luminance or some other reasonable metric.
I completely understand the desire to address the issue of content authors misusing or intentionally abusing HDR with some kind of auto-limiting algorithm similar to the way the radio 'loudness wars' were addressed. Unfortunately, I suspect it will be difficult, if not impossible, to achieve without also negatively impacting some content applying HDR correctly for artistically expressive purposes. Static photos may be solvable without excessive false positive over-correction but cinematic video is much more challenging due to the dynamic nature of the content.
As a cinemaphile, I'm starting to wonder if maybe HDR on mobile devices simply isn't a solvable problem in practice. While I think it's solvable technically and certainly addressable from a standards perspective, the reality of having so many stakeholders in the mobile ecosystem (hardware, OS, app, content distributors, original creators) with diverging priorities makes whatever we do from a base technology and standards perspective unlikely to work in practice for most users. Maybe I'm too pessimistic but as a high-end home theater enthusiast I'm continually dismayed how hard it is to correctly display diverse HDR content from different distribution sources in a less complex ecosystem where the stakeholders are more aligned and the leading standards bodies have been around for many decades (SMPTE et al).
I believe everything could be solved the same way we solved high dynamic range in audio, with a volume control.
I find it pretty weird that all tvs and most monitors hide the brightness adjustment under piles and piles of menus when it could be right there in the remote alongside the sound volume buttons. Maybe phones could have hardware brightness buttons too, at least something as easy as it is on adjusting brightness in notebooks that have dedicated brightness fn buttons.
Such brightness slider could also control the amount of tonemapping applied to HDR content. High brightness would mean no to low tonemapping and low brightness would use a very agressive tonemapper producing a similar image to the SDR content along it.
Also note that good audio volume attenuation requires proper loudness contour compensation (as you lower the volume you also increase the bass and treble) for things to sound reasonably good and the "tone" sound well balanced. So, adjusting the tonemapping based on the brightness isn't that far off what we do with audio.