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I thought you were saying the TV industry is fixing it, maybe I misunderstood. PQ is a television standard, people don’t really use it in other scenarios. I tho

by dahart 1y ago

I thought you were saying the TV industry is fixing it, maybe I misunderstood. PQ is a television standard, people don’t really use it in other scenarios. I thought you were defending PQ. If not, then I’m not sure why we’re talking about PQ, Game Maker doesn’t use PQ, does it? I’m not sure what you mean about different ambient environments leading to the conclusion that PQ is wrong. No color space can fix that problem, that’s not a color space problem. You seemed to argue with the idea of keeping track of physical units. I guess I’m not understanding your point. For the rest it sounds like we’re mostly in full agreement. Of course the output of HDR work isn’t linear, transfer functions and tonemapping guarantee that. I mentioned linear HDR workflows because you brought up PQ, which is primarily a delivery display color space for HDR displays. I agree that what 1.0 means depends on what the color space defines it to mean, especially when you don’t use a relative color space. We only have the 2 kinds, one that’s relative and where 1.0 is defined to mean the max brightness (or reflectivity) of the display medium, and one where you somewhere define an absolute reference point. My point was only, and still is, that for the relative color spaces, 1.0 always means the same thing. It’s true you can have values above 1 in a relative color space, if you want, but you can’t print or display them; that would only be useful for pre-output color processing.

kllrnohj 1y ago
> We only have the 2 kinds, one that’s relative and where 1.0 is defined to mean the max brightness (or reflectivity) of the display medium, This is just not true though. The most common relative colorspaces have 1.0 as an arbitrary user brightness setting, not the max brightness. This is where >1.0 values typically gain meaning and the typical "0-1 is ldr, >1 is hdr" comes from. This requires a float format for output. (linear) extended srgb is a standard example, but also Apple's EDR. But you can also have relative colorspaces where 1.0 is a value brighter than SDR white. This is critical for unorm formats which are typically much more efficient for display. HLG is a standard example of this, but Android's extended range brightness is another. > Game Maker doesn’t use PQ, does it? I have no idea what its HDR support looks like. If it can produce an HDR output on screen it's probably using PQ to do it since that's the most broadly supported option. PQ being crap though is why if you've ever played a game in HDR it pushes you to do a calibration wizard first
- dahart 1y ago
  > The most common relative colorspaces have 1.0 as an arbitrary user brightness setting, not the max brightness. You’re using different words to say the exactly same thing I was trying to say. You’re not arguing with me, you’re agreeing. Your “arbitrary brightness” means the same thing I meant by “max brightness”, because I meant max brightness as the maximum brightness the device will display at its current arbitrary settings, not the absolute maximum brightness the device is capable of if you change the settings later. It would be better if you take a moment to think in terms of print rather than only video standards. You can’t change the brightness of paper. 1.0 always means reflect all the light you can reflect, and there is no brightness setting. Because print is reflective and not emissive, print always takes relative colors. The analogy extends pretty naturally to TVs at a given brightness setting. The most common relative colorspaces (by which I mean the old crappy non-perceptual ones like RGB, HSV, CMYK) are still relative, meaning the brightest colors they represent (what we’re calling 1.0) map to the brightest the display will do at that moment in time. SDR, like PQ, is a video standard and has an absolute reference point (100 nits), so of course any relative color space can have a 1.0 value greater than SDR white, because most TVs these days can exceed 100 nits. Is that what you mean? I don’t see why that’s relevant to what 1.0 means in other color spaces. You still haven’t really explained what’s wrong with PQ. I’ve never used it directly, but do you have any links or any explanation to support your claim that it’s “wrong”? Why is it wrong? What color spaces are doing it right? If people use ACES shaders in GameMaker, as the article discussed, doesn’t that automatically mean that GameMaker is not using PQ? It doesn’t make any sense to have PQ after tonemapping. Maybe as a compression technique / format that the video card and the display use transparently without any interaction with the user or the application, but that’s not GameMaker, its the TV. I still don’t understand why we’re talking about PQ. To circle back to my main point, I still believe that using physical units is the most important part of HDR conceptually. You seemed to disagree, but this entire discussion so far only seems to make that point even more clear and firm, and as far as I can tell you agree. IMO the canonical color space for HDR and best example would be linear float channels where 1.0 is defined as 1.0 nits (or substitute for another physical luminance unit). HDRI’s strengths and utility is in capture, storage, and intermediate workflows, and not output. As soon as you target a specific type of device, as soon as you tack on a transfer function, tonemapping, or lower bit rate, you’re limiting options and losing information.

by dahart 1y ago

kllrnohj 1y ago

> We only have the 2 kinds, one that’s relative and where 1.0 is defined to mean the max brightness (or reflectivity) of the display medium, This is just not true though. The most common relative colorspaces have 1.0 as an arbitrary user brightness setting, not the max brightness. This is where >1.0 values typically gain meaning and the typical "0-1 is ldr, >1 is hdr" comes from. This requires a float format for output. (linear) extended srgb is a standard example, but also Apple's EDR. But you can also have relative colorspaces where 1.0 is a value brighter than SDR white. This is critical for unorm formats which are typically much more efficient for display. HLG is a standard example of this, but Android's extended range brightness is another. > Game Maker doesn’t use PQ, does it? I have no idea what its HDR support looks like. If it can produce an HDR output on screen it's probably using PQ to do it since that's the most broadly supported option. PQ being crap though is why if you've ever played a game in HDR it pushes you to do a calibration wizard first

dahart 1y ago
> The most common relative colorspaces have 1.0 as an arbitrary user brightness setting, not the max brightness. You’re using different words to say the exactly same thing I was trying to say. You’re not arguing with me, you’re agreeing. Your “arbitrary brightness” means the same thing I meant by “max brightness”, because I meant max brightness as the maximum brightness the device will display at its current arbitrary settings, not the absolute maximum brightness the device is capable of if you change the settings later. It would be better if you take a moment to think in terms of print rather than only video standards. You can’t change the brightness of paper. 1.0 always means reflect all the light you can reflect, and there is no brightness setting. Because print is reflective and not emissive, print always takes relative colors. The analogy extends pretty naturally to TVs at a given brightness setting. The most common relative colorspaces (by which I mean the old crappy non-perceptual ones like RGB, HSV, CMYK) are still relative, meaning the brightest colors they represent (what we’re calling 1.0) map to the brightest the display will do at that moment in time. SDR, like PQ, is a video standard and has an absolute reference point (100 nits), so of course any relative color space can have a 1.0 value greater than SDR white, because most TVs these days can exceed 100 nits. Is that what you mean? I don’t see why that’s relevant to what 1.0 means in other color spaces. You still haven’t really explained what’s wrong with PQ. I’ve never used it directly, but do you have any links or any explanation to support your claim that it’s “wrong”? Why is it wrong? What color spaces are doing it right? If people use ACES shaders in GameMaker, as the article discussed, doesn’t that automatically mean that GameMaker is not using PQ? It doesn’t make any sense to have PQ after tonemapping. Maybe as a compression technique / format that the video card and the display use transparently without any interaction with the user or the application, but that’s not GameMaker, its the TV. I still don’t understand why we’re talking about PQ. To circle back to my main point, I still believe that using physical units is the most important part of HDR conceptually. You seemed to disagree, but this entire discussion so far only seems to make that point even more clear and firm, and as far as I can tell you agree. IMO the canonical color space for HDR and best example would be linear float channels where 1.0 is defined as 1.0 nits (or substitute for another physical luminance unit). HDRI’s strengths and utility is in capture, storage, and intermediate workflows, and not output. As soon as you target a specific type of device, as soon as you tack on a transfer function, tonemapping, or lower bit rate, you’re limiting options and losing information.