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Apple’s “Extended Dynamic Range” Brings HDR to Non-HDR Displays

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Re: Apple’s “Extended Dynamic Range” Brings HDR to Non-HDR Displays

#11

Post by skavi »

nitrogen wrote: post #4
renewiltord wrote: post #3

I wonder how a large organization does something like this successfully. Like you need your OS video driver team working with the application team and so on. My impression is that PMing this is really hard. And then each of the other guys is going to have an opinion that this shouldn't be done because it's so rare, etc. Something must be organizationally right for something like this capable engineering to have succe…

Colorimetry is standardized. The W3C has been asking the same questions about mixing HDR and SDR, as have various other standards orgs like SMPTE: https://drafts.csswg.org/css-color-hdr/#Compositing-SDR-HDR

doesn’t make it easy to implement. Microsoft definitely hasn’t done great.

Re: Apple’s “Extended Dynamic Range” Brings HDR to Non-HDR Displays

#12

Post by ineedasername »

I think I must be some weird outlier on HDR. I recently upgraded to a display that supports it, and when I turn it on, everything just looks darker to me. As though the brightness went to half at the same time that contrast was cranked up high. Playing with color and exposure and other settings just made things worse.

Re: Apple’s “Extended Dynamic Range” Brings HDR to Non-HDR Displays

#13

Post by AnssiH »

When still talking about mixed SDR+HDR content on a HDR display having differently mapped whites, the article says:

> it’s strange and new, and possibly unique to Apple.

But that is exactly how Windows 10 does it with HDR displays, too. So not really unique to Apple. To the article's benefit, it did say "possibly" :)

I'm using Win 10 myself with an HDR display, and HDR white appears brighter than "desktop" white just like in the article photo.

There is also a slider in Win10 HDR settings that allows you to bring SDR/"desktop" white up if you wish to oversaturate SDR.

Re: Apple’s “Extended Dynamic Range” Brings HDR to Non-HDR Displays

#15

Post by mceachen »

ineedasername wrote: post #12

I think I must be some weird outlier on HDR. I recently upgraded to a display that supports it, and when I turn it on, everything just looks darker to me. As though the brightness went to half at the same time that contrast was cranked up high. Playing with color and exposure and other settings just made things worse.

HDR needs a bunch of things to work correctly:

1) the software needs to render with the correct gamut profile (typically "P3.display")

2) the OS needs to have a reasonable color profile for the display that knows about the higher gamut

3) the display needs to be in the correct mode to interpret and render in the correct gamut.

My LG HDR400 display only has 1 obvious setting for HDR as a "quick" setting, but it behaves like what you're said, and that just drops gamma.

Re: Apple’s “Extended Dynamic Range” Brings HDR to Non-HDR Displays

#16

Post by noobquestion81 »

AnssiH wrote: post #13

When still talking about mixed SDR+HDR content on a HDR display having differently mapped whites, the article says: > it’s strange and new, and possibly unique to Apple. But that is exactly how Windows 10 does it with HDR displays, too. So not really unique to Apple. To the article's benefit, it did say "possibly" :) I'm using Win 10 myself with an HDR display, and HDR white appears brighter than "desktop" white just…

apple uses this technique on non-HDR displays tho.

Re: Apple’s “Extended Dynamic Range” Brings HDR to Non-HDR Displays

#17

Post by kevingadd »

"On these non-HDR displays, Apple has remapped “white” to something less than 255-255-255, leaving headroom for HDR vales, should they be called for"

What is the source for this? I don't see any justification for this claim in the article. There are plenty of ways to implement this feature that don't involve permanently throwing out dynamic range on all your SDR panels. I'm not even convinced from reading this that they aren't HDR panels to begin with - the idea of an iPhone having a 9-bit or 10-bit panel in it isn't that strange to me, and while that wouldn't be enough for like Professional-Grade HDR it's enough that you could pair it with dynamic backlight control and convince the average user that it's full HDR.

Considering Apple controls the whole stack and uses a compositor there's nothing stopping them from compositing to a 1010102 or 111110 framebuffer and then feeding that higher-precision color data to the panel and controlling the backlight. Since they control the hardware they can know how bright it will be (in nits) at various levels.

Re: Apple’s “Extended Dynamic Range” Brings HDR to Non-HDR Displays

#18

Post by alin23 »

skavi wrote: post #6

> This EDR display philosophy is so important to Apple that they are willing to spend battery life on it. When you map “white” down to gray, you have to drive the LED backlight brighter for the same perceived screen brightness, using more power. Apple has your laptop doing this all the time, on the off chance that some HDR pixels come along to occupy that headroom. This is a bit misleading. The backlight isn’t at a h…

> When you map “white” down to gray, you have to drive the LED backlight brighter for the same perceived screen brightness

So that's why Lunar[1] reads a much higher brightness and makes all external monitors as bright as ten thousand suns when HDR content is played.

I wonder if there's any way to detect this and read or compute the SDR brightness instead.

[1] https://github.com/alin23/Lunar/issues/86

Re: Apple’s “Extended Dynamic Range” Brings HDR to Non-HDR Displays

#20

Post by rebuilder »

ineedasername wrote: post #12

I think I must be some weird outlier on HDR. I recently upgraded to a display that supports it, and when I turn it on, everything just looks darker to me. As though the brightness went to half at the same time that contrast was cranked up high. Playing with color and exposure and other settings just made things worse.

It sounds like a color profile mismatch. Specifically, it sounds like you're viewing linear light on something like an srgb profile without the proper color conversion. If pumping gamma up to 2.2 makes things look more or less normal, that's a strong indication it's an srgb issue.
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