[kllrnohj]

> To me, HDR feels like the system is ignoring my screen brightness settings.

On both Android & iOS/MacOS it's not that HDR is ignoring your screen brightness, but rather the brightness slider is controlling the SDR range and then yes HDR can exceed that, that's the singular purpose of HDR to be honest. All the other purported benefits of HDR are at best just about HDR video profiles and at worst just nonsense bullshit. The only thing HDR actually does is allow for brighter colors vs. SDR. When used selectively this really enhances a scene. But restraint is hard, and most forms of HDR content production are shit. The HDR images that newer iPhones and Pixel phones are capturing are generally quite good because they are actually restrained, but then ironically both of them have horrible HDR video that's just obnoxiously bright.

[frollogaston]

"On both Android & iOS/MacOS it's not that HDR is ignoring your screen brightness, but rather the brightness slider is controlling the SDR range and then yes HDR can exceed that"

Doesn't this mean HDR is ignoring my brightness setting? Looking at the Mac color profiles, the default HDR has some fixed max brightness regardless of the brightness slider. And it's very bright, 1600 nits vs the SDR max of 600 nits. At least I was able to pick another option capping HDR to 600, but that still allows HDR video to force my screen to its normal full brightness even if I dimmed it.

[kllrnohj]

> Doesn't this mean HDR is ignoring my brightness setting?

Not exactly because it is still being scaled by your brightness setting. As in, start playing an HDR video and then mess with the brightness slider. You will still see the HDR content getting dimmer/brighter.

It's easier to think about in Apple's EDR terms. 0.0-1.0 is the SDR range, and the brightness slider is changing what the nit value is of "1.0" - is it 100 nits? 300 nits? 50 nits? etc... HDR content (in theory) still has that same 0.0-1.0 portion of the range, and it's still being scaled. However it can exceed that 1.0. It's still being scaled, it's still "respecting" that slider. Just the slider wasn't a brightness limit as you're wanting it to be, but a 1.0 alignment point.

The problem comes when HDR content is disrespectful to that. When it just absolutely slams the brightness, pushing all of its content way past that 1.0 value. This is bad content, and unfortunately it's incredibly common in HDR media due in part to the fact that the original HDR specs are very incomplete and in part because it's a new loudness war.

[frollogaston]

Ah, just tested with https://github.com/dtinth/superwhite and you're correct. I remember it not even scaling with the brightness, but guess I was wrong.

[LinAGKar]

>HDR can exceed that

It's not just the HDR content that gets brighter, but SDR content too. When I test it in Chrome on Android, if an HDR image shows up on screen the phone start overriding the brightness slider completely and making everything brighter, including the phone's system UI.

>The only thing HDR actually does is allow for brighter colors vs. SDR.

Not just brighter, but also darker, so it can preserve detail in dark areas rather than crushing them.

[kllrnohj]

> It's not just the HDR content that gets brighter, but SDR content too. When I test it in Chrome on Android, if an HDR image shows up on screen the phone start overriding the brightness slider completely and making everything brighter, including the phone's system UI.

You have an "old" style handling of HDR on Android. Newer/better devices don't do that (specifically those that support https://source.android.com/docs/core/display/mixed-sdr-hdr )

Similarly MacOS/iOS doesn't do that.

> Not just brighter, but also darker, so it can preserve detail in dark areas rather than crushing them.

It does not get darker, and while PQ allocates more bits to the dark region HLG does not. And, more importantly, neither does the actual display panel which are still typically gamma 2.2-2.4 regardless. So PQ's extra precision in the dark areas is ~never utilized other than as tonemapping input, but the resulting output does not have any increased precision in the darks over SDR.

In fact it actually has less precision in the dark areas as the increased display luminance range means the panels native bit depth need to cover more range.

[agos]

you are right but at least in my experience it's very easy for a modern iPhone to capture a bad HDR photo, usually because there is some small strong highlight (often a form of specular reflection from a metallic object) that causes everything to be HDR while the photo content wouldn't need it

[altairprime]

In beta testing this morning, the Halide “HDR slider” works as intended to solve that. Some of my photos have only needed +0.3 while a couple taken in near-total no-light-pollution darkness have it cranked all the way to max and that still isn’t enough.

[BlueTemplar]

It isn't just about the brightness (range).

In practice the 'HDR' standards are also about wider color gamuts (than sRGB), and (as mentioned in parallel) packed into more bits, in a different way, so as to minimise banding while keeping file sizes in check.