[skavi]

> 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 higher level than necessary for sRGB content all the time, just whenever any HDR encoded videos or EDR apps are open. When you open an HDR video you can see the highlights getting brighter as the backlight gets pushed.

[crazygringo]

> just whenever any HDR encoded videos or EDR apps are open

Yup, I think this has to be the case. But the crazy thing is, I can't perceive any shift in UX brightness whatsoever, even a flicker, when I open/close an EDR video.

I would have thought that there would be some slight mismatch at the moment the backlight is brightened and pixels are darkened -- whether it would be a close but not perfect brightness match, or a flicker while they're not synced. But nothing.

As I mentioned in another comment, the only giveaway is that my cursor (mouse pointer) disappears for a second or two. I have to guess that adjusting its brightness happens at a different layer in the stack that can't be so precisely synced.

[skavi]

Yup, very impressive how well Apple has synced everything up. Definitely an advantage of controlling the whole stack.

[alin23]

> 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

[rdw]

Yes, this is what I came to see. It gradually increases the brightness over 5 seconds on my Catalina Macbook. It's very impressive that there are no visible brightness changes on the rest of the screen when the brightness of the backlight increases.

[Wowfunhappy]

Thank you. When I initially came to that paragraph, I went from being super impressed to being super concerned. Now I'm soundly back to impressed!

[gruez]

>When you open an HDR video you can see the highlights getting brighter as the backlight gets pushed.

but what about blacks? If you have a dark scene with bright highlights (eg. campfire at night), does the black parts of the scene get blown out because backlight bleed?

[dmitshur]

I wonder if this contributed to Apple removing the light-up Apple logo on the backs of MacBook screens. If it were still there, it would give it away when the backlight brightness is changing and potentially become distracting.