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The improvements coming for Wayland's HDR/color management are likely to help with that, as the features they're aiming for appears to beat Window's more slapda

The improvements coming for Wayland's HDR/color management are likely to help with that, as the features they're aiming for appears to beat Window's more slapdash implementation with per-window color management, where window contents are accurately tonemapped and composited within the widest color space the monitor supports. Adobe would need to be incentivized to port their suite over for it to be taken seriously, but maybe Wine could bridge that gap at first. Ah, the mythical Linux Desktop. One day...

jwells89 3y ago
Will Wayland be able to render mixed HDR and SDR content correctly, with e.g. an HDR video on YouTube rendering with extended range while the rest of the screen renders as normal? Currently only macOS can do that. With Windows you have to choose between SDR and HDR display modes which affects everything on screen regardless of type, which makes SDR content look dingy in HDR mode.
- kstrauser 3y ago
  On that subject, anyone know why shifting to HDR dims everything that way? My mental model of it is that SDR brightness goes from 0 to 100, and HDR brightness goes from -100 to 100, and that turning on HDR moves everything not HDR-aware down to the bottom of the brightness space. I could look this up, but never think about it outside of conversations like this and figure it might be more fun to talk about it.
  - wmf 3y ago
    It's more like SDR goes from 0 to 255 and HDR goes from 0 to 1024. In SDR mode, 255 = (say) 500 nits while in HDR mode 1024 = 1000 nits and thus 255 = 250 nits so SDR content looks dimmer.
  - dagmx 3y ago
    Consider that your display can only do 0-100 brightness (not really but for sake of argument) In SDR, you map the full SDR range (also 0-100) to that 0-100. When you add HDR, you’re now adding levels above 100 (let’s say 0-200). If your display can only do upto 100, you now need to put all the 0-100 stuff in 0-50. Or you get a display that can also display 0-200. Very few computer displays can do over a standard SDR range of 500 nits.
    - kstrauser 3y ago
      But why isn't SDR then scaled from 0-200, then? That is, why isn't "fully bright SDR" mapped to "fully bright HDR"?
      - saltcured 3y ago
        Well, it's pretty arbitrary. What is missing from most image (or sound) data is metadata to say what physical intensity is represented by the signal. I.e. how many nits (or decibels) should be emitted for this signal. AFAIK, most encoding standards only define a relative interpretation of the values within one data set. And even if standards did have a way to pin absolute physical ranges, many applications and content producers would likely ignore this and do their own normalization anyway, based on preconceptions about typical consumers or consumer equipment. To have a "correct" mixing, you would need all content to be labeled with its intended normalization, so that you can apply the right gain to place each source into the output. And of course there might be a need for user policy to adjust the mix. I think an HDR compositor ought to have gain adjustments per stream, just like the audio mixer layer.
      - dagmx 3y ago
        What context are you talking about? In single mode where it’s just SDR, it’s mapped to take the full range of the display up to whatever is deemed a comfortable cap. In a mixed HDR/SDR mode, the H is range above the S , so it doesn’t make sense to scale it up. I prefer Apple’s terminology of Extended Dynamic Range because it’s clearer that its range above the SDR range. Now you could say that you intend for that SDR to be treated as HDR, but without extra information you don’t know what the scaling should be. Doing a naive linear scale will always look wrong.
  - mmis1000 3y ago
    Because windows map sdr contents to srgb color space. Which nobody except designers uses. Most monitor today ship with a much brighter and, high contrast, vivid color profile by default. If you toggle your monitor to srgb color profile. You should see a color that looks really similar to sdr contents in Windows hdr mode. In my opinion, I also don't like it. But there is surely no way for Microsoft to chose a color profile that looks like without toggle hdr on given there are so many monitor manufacturers in the market. I think chose the most safe srgb option is understandable.
    - t0bia_s 3y ago
      Hopefully, DCI 3P will be standard in future. I have monitor that have 187% sRGB, 129% Adobe RGB and 133% DCI P3 gammut volume. But to have correct sRGB colors with maximum coverage on monitor I need to clamp ICC profile via Novideo SRGB. Without it, sRGB content looks oversaturated in orange spectrum.
  - bryanlarsen 3y ago
    A better way to describe it, IMO: SDR goes from 1-100. HDR goes from 0.01 to 100. Twice as many orders of magnitude difference from bottom to top. So if you peg the top to max brightness in both cases, the HDR looks brighter because the contrast is bigger. (Note that this is an analogy. In other words, it's wrong, but a way of looking at it)
LoganDark 3y ago
I am super excited for this, Wayland seems extremely promising. I'll probably try Fedora out again soon - my last experience with Wayland was GNOME and it was super nice.

jwells89 3y ago

Will Wayland be able to render mixed HDR and SDR content correctly, with e.g. an HDR video on YouTube rendering with extended range while the rest of the screen renders as normal? Currently only macOS can do that. With Windows you have to choose between SDR and HDR display modes which affects everything on screen regardless of type, which makes SDR content look dingy in HDR mode.

kstrauser 3y ago
On that subject, anyone know why shifting to HDR dims everything that way? My mental model of it is that SDR brightness goes from 0 to 100, and HDR brightness goes from -100 to 100, and that turning on HDR moves everything not HDR-aware down to the bottom of the brightness space. I could look this up, but never think about it outside of conversations like this and figure it might be more fun to talk about it.
- wmf 3y ago
  It's more like SDR goes from 0 to 255 and HDR goes from 0 to 1024. In SDR mode, 255 = (say) 500 nits while in HDR mode 1024 = 1000 nits and thus 255 = 250 nits so SDR content looks dimmer.
- dagmx 3y ago
  Consider that your display can only do 0-100 brightness (not really but for sake of argument) In SDR, you map the full SDR range (also 0-100) to that 0-100. When you add HDR, you’re now adding levels above 100 (let’s say 0-200). If your display can only do upto 100, you now need to put all the 0-100 stuff in 0-50. Or you get a display that can also display 0-200. Very few computer displays can do over a standard SDR range of 500 nits.
  - kstrauser 3y ago
    But why isn't SDR then scaled from 0-200, then? That is, why isn't "fully bright SDR" mapped to "fully bright HDR"?
    - saltcured 3y ago
      Well, it's pretty arbitrary. What is missing from most image (or sound) data is metadata to say what physical intensity is represented by the signal. I.e. how many nits (or decibels) should be emitted for this signal. AFAIK, most encoding standards only define a relative interpretation of the values within one data set. And even if standards did have a way to pin absolute physical ranges, many applications and content producers would likely ignore this and do their own normalization anyway, based on preconceptions about typical consumers or consumer equipment. To have a "correct" mixing, you would need all content to be labeled with its intended normalization, so that you can apply the right gain to place each source into the output. And of course there might be a need for user policy to adjust the mix. I think an HDR compositor ought to have gain adjustments per stream, just like the audio mixer layer.
    - dagmx 3y ago
      What context are you talking about? In single mode where it’s just SDR, it’s mapped to take the full range of the display up to whatever is deemed a comfortable cap. In a mixed HDR/SDR mode, the H is range above the S , so it doesn’t make sense to scale it up. I prefer Apple’s terminology of Extended Dynamic Range because it’s clearer that its range above the SDR range. Now you could say that you intend for that SDR to be treated as HDR, but without extra information you don’t know what the scaling should be. Doing a naive linear scale will always look wrong.
- mmis1000 3y ago
  Because windows map sdr contents to srgb color space. Which nobody except designers uses. Most monitor today ship with a much brighter and, high contrast, vivid color profile by default. If you toggle your monitor to srgb color profile. You should see a color that looks really similar to sdr contents in Windows hdr mode. In my opinion, I also don't like it. But there is surely no way for Microsoft to chose a color profile that looks like without toggle hdr on given there are so many monitor manufacturers in the market. I think chose the most safe srgb option is understandable.
  - t0bia_s 3y ago
    Hopefully, DCI 3P will be standard in future. I have monitor that have 187% sRGB, 129% Adobe RGB and 133% DCI P3 gammut volume. But to have correct sRGB colors with maximum coverage on monitor I need to clamp ICC profile via Novideo SRGB. Without it, sRGB content looks oversaturated in orange spectrum.
- bryanlarsen 3y ago
  A better way to describe it, IMO: SDR goes from 1-100. HDR goes from 0.01 to 100. Twice as many orders of magnitude difference from bottom to top. So if you peg the top to max brightness in both cases, the HDR looks brighter because the contrast is bigger. (Note that this is an analogy. In other words, it's wrong, but a way of looking at it)

LoganDark 3y ago

I am super excited for this, Wayland seems extremely promising. I'll probably try Fedora out again soon - my last experience with Wayland was GNOME and it was super nice.