[Androider]

The Windows HDR implementation is complete crap, exactly because they don't have have full control of the hardware stack as Apple does and can't change all the monitor settings like they would need to.

When you toggle HDR on Windows, the desktop becomes dull gray and desaturated exactly because they pull down the previous desktop brightness to something less than 255. So you have to then adjust your monitor's brightness up to compensate. The monitor's brightness effectively sets the upper cap of the HDR brightness, so let's say your brightness was set at 50% before, now you've got to fiddle with the monitor to boost the screen brightness to 100% to allow HDR to function, and to achieve your previous desktop white brightness (you'll probably also have to adjust the software "desktop white" point slider you mentioned, since MS has no clue what the correct monitor brightness and SDR pull down amount should be, so good luck matching your previous desktop colors and brightness). In my experience very few people successfully manage to setup their Windows HDR correctly, and even if you do there's no way to "seamlessly" switch between the two modes (which you have to do since tons of stuff on Windows doesn't work properly when HDR mode is enabled). I haven't checked Surface or other MS hardware, perhaps they're able to do something more clever there?

What Apple does, is that when your display brightness is 50% and you display HDR content, the HDR content will seamlessly appear at a brightness somewhere between 75% to 100% of the maximum screen brightness. That is a seamless HDR effect, giving you the whiter than white experience next to your other windows that just works.

[AnssiH]

I haven't encountered such issues with LG C9. I don't need to touch the settings on my TV when enabling/disabling Windows HDR (which puts my TV in HDR mode), the previous SDR-mode desktop brightness is achieved in HDR mode just fine.

Though I remember having read that the Windows HDR stuff works slightly differently for internal monitors (e.g. in laptops), is your experience with those?

[jasomill]

I imagine this depends on the configuration of the TV, if only because — if your C9 is anything like my slightly older LG IPS HDR TV — backlight brightness, color calibration, and other settings that affect the brightness of full-scale SDR white can be freely configured in any of the SDR modes without affecting the levels of any other SDR mode, or of any HDR mode at all.

In other words, assume SDR "Game" mode is set to Backlight 50, SDR "Cinema" mode is set to backlight 25, all other settings are equal, and, therefore, 100% white is considerably brighter in "Game" mode.

Then both values for "white" cannot possibly match a single, fixed level set by any other mode, HDR or otherwise.

It's therefore impossible for Windows or any other input source to "just work" when switching from an arbitrary SDR mode to a preset HDR mode.

Again, assuming your TV works more or less like mine, and mode switches use the most-recently-used preset in the target "mode family" (meaning not only SDR and HDR, but also Dolby Vision, which maintains its own collection of presets), and that the various presets are independent of one another.

And if this is not the case, and presets cannot be set independently, then I'm glad I don't have a newer TV, because some of my presets have color settings that are wildly different from standard calibration (e.g., a preset resetting the display to its native, uncalibrated white point and gamut, used with video players capable of internal HDR tone mapping and color correction given a custom 3D LUT generated from measurements).

[ttul]

Dolby Vision traces its origins to the acquisition of Brightside Technologies (https://en.wikipedia.org/wiki/BrightSide_Technologies), which was itself a spin-off from a group at the University of British Columbia. I wonder how extensively Dolby has profited from the patents it accumulated via that acquisition, since many of the key ideas behind HDR displays must surely be covered by them.

[buildbot]

Huh, when I started as a Master's student at UBC we got a tour of some of the labs in the ECE and CS departments there, one of which was the media lab that had one of this HDR displays. I remember being blown away by how realistic the display looked compared to an SDR display. It's cool that some of their tech lives on!

[boromi]

So how exactly do we correctly set HDR on Windows?

You have the HDR/SDR brightness balance to set and the monitor's own contrast adjustments.

[shock-value]

It can also be argued that Apple’s approach is a bit user-hostile. If someone wants their display at a 50% brightness ceiling (e.g. working in a darker room) it would be jarring to see HDR content overriding that, especially as such content becomes more prevalent.