HDR support for Windows

[LinDen]

Firefox managed to bring HDR to Macs in 100.0 version. Now it's time for Windows!

It'd be awesome to watch and work on HDR images and videos using Firefox in 2022. Windows is the most popular OS, why not bring HDR here too?
More monitors and devices running on Windows support HDR, so there is an increase in demand of HDR support in Firefox.

The only option for Windows users is either to switch to another browser or to download and use a dedicated app from Microsoft Store.

[groslol]

Hello @itskaren , everyone

 I've been following this thread since I got my Dolby Vision monitor (2 years ago). Switched to brave for this exact feature and then goes back to Firefox ... On all OS possible. I've tested the nighlty build, and oh god ... I know this is experimental but come on, 4 years and this is what you made HDR looks like ...?

 For reference, this is a comparison of Firefox, Firefox Nightly with HDR and Edge with HDR. All on the same YouTube video and same timestamp. All displayed on a AW3225QF 4K Dolby Vision (With everything HDR related turned on and working well (As you can see on the Edge example)). Photos have been taken with an iPhone 15 Pro Max (On x1). You can find both compressed JPG and Full DNG files for comparison. Only source of light is the screen, no other lights. Even if the photos are clearly not 100% reality the Firefox Nightly HDR is washed out. Like playing HDR on a non HDR device. It feels like amateurism after all those years... Sorry to say that, even if it's experimental...

On the photo named FirefoxHDR-Edge, on the left is the nightly build with washed out color and on the right the Edge, really great HDR rendering (Clearly way better than SDR).

On the photo named FirefoxSDR-FirefoxHDR, on the right is latest Firefox stable release (147.0.2 atm) and on the right the 149.0a nightly build (So not even 148a...)

Links for pictures: 
- GoFile: https://gofile.io/d/HJVg6L
- Buzzheavier (Backup): 
  - https://buzzheavier.com/rw93vtyl8a33
  - https://buzzheavier.com/6m7yqc6tjxnx
  - https://buzzheavier.com/uvsjle9iuzgu
  - https://buzzheavier.com/6jrdp141ey8r
 
Kind Regards,

[TexelGuy]

@groslol Try setting the about:config pref 'media.wmf.force.allow-p010-format' to true and restarting the browser. HDR looks correct for me after doing that. This pref is going to be enabled by default in Nightly in the future: https://bugzilla.mozilla.org/show_bug.cgi?id=2012852