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by kllrnohj 422 days ago
> my macbook screen literally goes darker AROUND the video , which gets brighter. I am not making this up

This is almost certainly your eyes playing tricks on you, actually. Setup that situation where you know if you scroll down or whatever it'll happen, but before triggering it cover up the area where the HDR will be with something solid - like a piece of cardboard or whatever. Then do it. You'll likely not notice anything change, or if there is a shift it'll be very minor. Yet as soon as you remove that thing physically covering the area, bam it'll look gray.

It's a more intense version of the simultaneous contrast illusions: https://en.wikipedia.org/wiki/Contrast_effect & https://en.wikipedia.org/wiki/Checker_shadow_illusion

Eyes be weird.
1 comments
astrange 422 days ago
The screen is literally getting darker so the HDR video will appear to have more contrast.

https://prolost.com/blog/edr

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kllrnohj 422 days ago
No, it literally isn't. It's literally doing the opposite, it increases the display brightness in order to show the HDR content. The SDR content is dimmed proportional to the increase such that SDR has the same emitted brightness before & after the change.

SDR brightness is not reduced to "add contrast". The blog post doesn't seem to say that anywhere, either, but if it does it's simply wrong. As a general note it seems wrong about a lot of aspects, like saying that Apple does this on non-HDR displays. They don't. It then also conflates EDR with whether or not HDR is used. EDR is simply the representation of content between apps & the compositor. It's a working space not entirely unlike scRGB where 0.0-1.0 is simply the SDR range, and it can go beyond that. But going beyond the maximum reported EDR range, which can be as low as 1.0, the result is simply clipped. So they are not "simulating" HDR on a non-HDR display.

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astrange 422 days ago
I agree with what you said, but I was trying to give the layman summary ;)

> The SDR content is dimmed proportional to the increase such that SDR has the same emitted brightness before & after the change.

That's the intent, but because things aren't perfect it actually tends to get darker instead of stay perceptually the same. It depends on which panel you're using. MBPs are prone to this, XDR displays aren't.

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kllrnohj 422 days ago
> I agree with what you said, but I was trying to give the layman summary ;)

Your layman summary is wrong, though. Brightness stays the same is the summary, whereas you said it gets darker.

> MBPs are prone to this, XDR displays aren't.

On my M1 16" MBP it doesn't have any issue. The transition is slow, but the end result is reasonably aligned to before the transition. But yes MBP displays are not Apple's best. Sadly that remains something exclusive to the iPad

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