What are the risks of doing this? I would love to ramp up the nits for outside work, but presumably it's been limited to 500 nits for SDR for a reason.
But 2 things should be considered:
1. If most of the screen is not full bright white, (e.g. white text on dark background), then LEDs will have plenty of time to cool down
2. macOS has hard temperature thresholds, and limits the brightness when the display gets too hot: https://www.pcmag.com/news/apple-xdr-displays-limit-brightne...
Note that the display is not an OLED display, but a regular IPS LCD with local dimming zones for the backlight[1]. Thus only the dimming zones not covered by white text would get to cool off.
This also points to another downside of pushing up the nits: it will likely increase the bleed-through of the backlight, driving up the black level especially in white-text-on-black scenarios.
Also they want HDR to be a selling point. Not many phones take HDR videos and images. "It goes brighter" is what makes HDR pop.
1,600 nits is useful for working indoors next to a large window.
The comfortable amount of nits is entirely dependent on ambient lighting conditions.
Next to a window, 1600 nits can look dim.
What Apple is doing now looks terrible because SDR and HDR do not coexist well at all. Any HDR video even ones that you wouldn't think would be "bright", blow up the screen while your SDR content next to it is now hard to read. HDR and SDR should have a comparable average brightness level with only "highlights" going "brighter than bright", but that's not what they do, they make the entire video brighter. People want uniform brightness. If I want my entire screen to go bright, I can set the damn brightness myself.
This is exactly how it works. When I open a video and switch between 500 nits and 1600 nits in Display Preferences, everything looks exactly the same, except for the highlights in the video. Of course outdoors daylight scenes will have a higher average brightness.
There is no point to 'high dynamic range' if a bright sky is the same brightness as a sheet of paper, or your website background; it's supposed to represent real-life brightness and contrast in photography & video, and there is no reason for your graphical interfaces to reach those light levels, i.e. Slack's white background should not be close in brightness to a cloudy sky. If they didn't "limit" non-HDR content to 500 nits (again, already above the average monitor), how would it be possible to have HDR at all?
I don't see how the content could become harder to read, when the light output is exactly the same. Your description reminds me of a shitty Benq 'HDR400' monitor, which would artificially limit the light output for non-HDR content making it gray and dull. That is not the case with the mini-led macs or better HDR monitors. Some examples of decent HDR - these look fine next to a browser or anything else on a MBP 14", and also in Windows with HDR on:
https://www.youtube.com/watch?v=vX2vsvdq8nw
https://www.youtube.com/watch?v=5brujY1PvpY
If you have any counter-examples or the particular setup you think looks bad, I'm curious to try it myself.
Not in my experience. I've seen iPhone videos that were entirely in the HDR range despite being indoor scenes in ambient lighting lit from a single window.
> There is no reason for your graphical interfaces to reach those light levels,
Again, I'm using Lunar right now and I find it useful sitting in next to my window. Not sure how that can be considered "no reason". It's literally useful to me right now as I use it.
> how would it be possible to have HDR at all?
It doesn't have to be possible! I don't use HDR. I don't care that theoretically HDR content would clip. It's not on my screen.
I'd rather HDR just use the same brightness range as SDR. Let me choose myself where HDR maps compared to SDR. I really do not want HDR as it is implemented today.
> I don't see how the content could become harder to read,
My eyes adjust to the HDR average picture level, and then SDR appears too dim.
Some of these problems stem from bad HDR tone mapping. But regardless, I want to control where SDR white maps because my workspace is bright. And I enjoy well lit rooms.