This does seem to be very specific to Game Maker though. Like saying 0.0-1.0 is 8 bit unorm is incorrect. It's just a unorm, no bit depth is otherwise implied. Similarly HDR doesn't mean exceeding 1.0. It can mean that, but if you're going to a display directly you're going to want something more like 101010X2 unorm in PQ, which is still 0.0-1.0 in the fragment shader
> This does seem to be very specific to Game Maker though.
Good point. I was going to point out that in general comparing 6-bit color to float color should not result in a change in brightness, tonemapping, or anything other than maybe some visible quantizing in the 6-bit version. That first example makes sense to me if we’re talking about what Game Maker does with 6bpp vs float, and wasn’t meant to be a conceptual comparison of bit depths for shaders in any environment. So maybe GM doesn’t use the same color pipeline with LDR vs HDR colors, perhaps HDR is tonemapped and LDR isn’t? The first paragraph implies this, but doesn’t say it explicitly. Or is tonemapping in GM a user choice not determined by color format?
> Similarly HDR doesn’t mean exceeding 1.0
True, but it’s harder to see the point of HDR without having to deal with colors that are brighter than the display can handle.
There are lots of different ideas & suggested definitions around for what HDR means, but I like to think the important one is the idea of storing colors in absolute physical units, as opposed to relative units where 1.0 means one times the brightest color the display is capable of. Which, of course, you can do with any bit depth, but HDR tends to pair well with higher bit depths.
> True, but it’s harder to see the point of HDR without having to deal with colors that are brighter than the display can handle.
1.0 is a completely arbitrary value that has no meaning. When used with sRGB 1.0 means "users brightness setting." When used with PQ, 1.0 means 10,000 nits. When used with HLG 1.0 means "idk maybe 1000 nits? nobody knows!"
You need the colorspace to be defined to know what 1.0 means and whether or not it represents an SDR or HDR value. Or if it's neither even and maps directly to the current display range.
Presumably game maker has fixed opinions here, but that gets back to "this is very game maker specific"
> but I like to think the important one is the idea of storing colors in absolute physical units,
That is not only the least important aspect of PQ HDR, it's downright wrong and the industry is fixing that bug :)
You'd do that at the OS level, games don't need to re-invent that. Games do now ship with HDR calibration wizards to deal with the particular aspect of luminance range and SDR white point being totally undefined and inconsistent, at least for almost anything connected via HDMI or DisplayPort
No proper calibration, but the closest I've seen is in the Myst series. According to my fuzzy memory, either Riven or Exile (or both) had a setup screen with shades of gray, it instructed you to adjust the brightness / contrast of your monitor until the shades looked a certain way. My search-fu is failing me on this, so maybe it's a fabricated memory.
As a dev I always hope that the user's monitor is calibrated. The situation is definitely better than it was 20 years ago, with a lot more monitors coming from the factory with better defaults, especially Apple devices, but you really need a color calibration widget to do it properly, e.g.
This does seem to be very specific to Game Maker though. Like saying 0.0-1.0 is 8 bit unorm is incorrect. It's just a unorm, no bit depth is otherwise implied. Similarly HDR doesn't mean exceeding 1.0. It can mean that, but if you're going to a display directly you're going to want something more like 101010X2 unorm in PQ, which is still 0.0-1.0 in the fragment shader
> This does seem to be very specific to Game Maker though.
Good point. I was going to point out that in general comparing 6-bit color to float color should not result in a change in brightness, tonemapping, or anything other than maybe some visible quantizing in the 6-bit version. That first example makes sense to me if we’re talking about what Game Maker does with 6bpp vs float, and wasn’t meant to be a conceptual comparison of bit depths for shaders in any environment. So maybe GM doesn’t use the same color pipeline with LDR vs HDR colors, perhaps HDR is tonemapped and LDR isn’t? The first paragraph implies this, but doesn’t say it explicitly. Or is tonemapping in GM a user choice not determined by color format?
> Similarly HDR doesn’t mean exceeding 1.0
True, but it’s harder to see the point of HDR without having to deal with colors that are brighter than the display can handle.
There are lots of different ideas & suggested definitions around for what HDR means, but I like to think the important one is the idea of storing colors in absolute physical units, as opposed to relative units where 1.0 means one times the brightest color the display is capable of. Which, of course, you can do with any bit depth, but HDR tends to pair well with higher bit depths.
> True, but it’s harder to see the point of HDR without having to deal with colors that are brighter than the display can handle.
1.0 is a completely arbitrary value that has no meaning. When used with sRGB 1.0 means "users brightness setting." When used with PQ, 1.0 means 10,000 nits. When used with HLG 1.0 means "idk maybe 1000 nits? nobody knows!"
You need the colorspace to be defined to know what 1.0 means and whether or not it represents an SDR or HDR value. Or if it's neither even and maps directly to the current display range.
Presumably game maker has fixed opinions here, but that gets back to "this is very game maker specific"
> but I like to think the important one is the idea of storing colors in absolute physical units,
That is not only the least important aspect of PQ HDR, it's downright wrong and the industry is fixing that bug :)
Would love to hear why Tonemap_Uncharted2 has a range from 0.00-0.93. Seems like a weird choice.
Going of on tangent asking this but have any games ever shipped with colour charts for calibration with different monitors?
You'd do that at the OS level, games don't need to re-invent that. Games do now ship with HDR calibration wizards to deal with the particular aspect of luminance range and SDR white point being totally undefined and inconsistent, at least for almost anything connected via HDMI or DisplayPort
No proper calibration, but the closest I've seen is in the Myst series. According to my fuzzy memory, either Riven or Exile (or both) had a setup screen with shades of gray, it instructed you to adjust the brightness / contrast of your monitor until the shades looked a certain way. My search-fu is failing me on this, so maybe it's a fabricated memory.
A significant fraction of games I've played on Xbox in the last decade have had a setup like that.
As a dev I always hope that the user's monitor is calibrated. The situation is definitely better than it was 20 years ago, with a lot more monitors coming from the factory with better defaults, especially Apple devices, but you really need a color calibration widget to do it properly, e.g.
https://www.amazon.com/Version-Datacolor-Spyder-Monitor-Cali...
Nice succinct article. Thanks.