5 ms·

So, I'll admit to being a Luddite on the whole HDR thing, but I suppose it's worth figuring out in the case it becomes commonplace and not another fad like 3D T

So, I'll admit to being a Luddite on the whole HDR thing, but I suppose it's worth figuring out in the case it becomes commonplace and not another fad like 3D TV. How does HDR affect colors in software? For example, on a 10-bit display - does my "legacy" website showing #FFF, show a true brightest-white color, or would I need to use a special definition to achieve it? Unfortunate, as I'm sure the hex value for a 10-bit 3-tuple is not quite as "perfect" as #000000-#FFFFFF. e.g. like `color: rgbhdr(#0x3FF3FF3FF)` If I use a non-HDR-aware color-picker app (or take a screenshot), and pick HDR content versus normal content, is there a translation layer that scales down the value to RGB? Or does it clamp and "overexpose"? It's a whole new world. I googled "HDR in CSS" and got this[0] which is not quite "stubborn programmer who thinks this is a gimmick" friendly... Anyone have a good resource that explains how one would use HDR colors in practice? And ideally one that touches on considerations like the interactions between HDR-aware and non-HDR-aware applications. [0]: https://w3c.github.io/ColorWeb-CG/ https://w3c.github.io/ColorWeb-CG/

friedman23 6y ago
> but I suppose it's worth figuring out in the case it becomes commonplace and not another fad like 3D TV. HDR is already here to stay
munchbunny 6y ago
I think it's a big fat "it depends". For example, do GIFs even do HDR? And is there a 10-bits-per-channel specification for PNG's? (I haven't tried to look that up.) Since HDR is a superset of the non-HDR color space, I suspect there will be not that much fuss converting 8-bit to 10-bit, but a whole lot of "magic" involved in converting 10-bit down to 8-bit.
- dmitshur 6y ago
  PNG supports up to 16-bit depth, and it’s actually a good choice based on an analysis[1] Netflix did in 2018. [1]: https://netflixtechblog.com/enhancing-the-netflix-ui-experience-with-hdr-1e7506ad3e8 https://netflixtechblog.com/enhancing-the-netflix-ui-experie...
the8472 6y ago
Most content will be rendered in sRGB by default. Things will have to opt into WCG/HDR. For CSS specifically you can already opt into WCG via color-gamut, but not into HDR yet. I.e. you can have greener greens but not the whitest white. > which is not quite "stubborn programmer who thinks this is a gimmick" friendly... Perhaps this draft is more readable. https://drafts.csswg.org/css-color-hdr/ https://drafts.csswg.org/css-color-hdr/
- ly 6y ago
  I’m working on a website with WCG colors right now, and in practice you’re mostly right: Chrome and related browsers only support sRGB, and will thus only show sRGB colors. In Safari you can opt in to use display-p3 for colors in CSS, and it will display those as WCG and everything else still as sRGB. This looks amazing. However, there’s Firefox which only supports sRGB, but then displays everything in WCG completely over saturating every single colored pixel on a website [1]. The only way to get your website to look the way you intended it on Firefox is to make the whole thing black and white. [1] https://www.reddit.com/r/firefox/comments/dloon6/solving_firefoxs_color_saturation_issue_on_wide/ https://www.reddit.com/r/firefox/comments/dloon6/solving_fir...
dmitshur 6y ago
I’d suggest reading https://netflixtechblog.com/enhancing-the-netflix-ui-experience-with-hdr-1e7506ad3e8 https://netflixtechblog.com/enhancing-the-netflix-ui-experie..., it’s quite accessible and gives a good overview of the space.
JohnBooty 6y ago
Here's the best practical demonstration I've found; it's about as well as can be accomplished considering we're talking about looking at pictures of HDR on non-HDR displays. https://prolost.com/blog/edr https://prolost.com/blog/edr It's decidedly not a gimmick. However, it not exactly magic either, and to extent it really relies on the effectiveness of your display's local dimming and maximum brightness. If you're running your display at 50% brightness, then yeah... it's got "more brightness to spare" when it's time to render those extra brighter-than-bright areas. If you're running your display at max 100% brightness already then... well, there's nowhere to go from there. I briefly played around with my 2018 iPad Pro, which has an EDR display. I watched the Apple TV movie "Greyhound" with Tom Hanks. That movie appears to have been shot as something of a demo for HDR rendering. Lots of shots inside the dark, cramped ships, with INTENSELY bright light coming in thru the windows. Watching it on the iPad, the windows were WAY brighter than the rest of the ship interior. But, I could still see everything in the ship interior. It wasn't lost in the shadows. Watching it on my nice Dell IPS monitor, it looked totally different. The portholes were brighter than the ship interior, but not by much. It just looked like a normal movie. It was a very convincing demo. However, perhaps hilariously, I thought it looked better in non-HDR on my Dell. Nonetheless, it was an impressive tech demo.
hatsunearu 6y ago
Hijacking for visiblity: Is there a way of mastering pictures for "real" HDR--not the fake compressed dynamic range crap, but with the right software switches to "turn on" the magic high dynamic range mode through the OS? HDR video specifically has a metadata tag that allows the stream to be correctly viewed on your fancy TV by turning on all the right hardware and software "HDR switch"--like increasing max brightness to the set luminance value in the metadata, etc. For HEIC pictures taken on iPhone, the right switches are turned on in iOS and macOS. Wondering if it's possible to create pictures from my regular sony a7r4 with those metadata tags so it can look cool on fancy displays. I've literally asked everywhere including my workspace Slack (big company) and nobody knows. The only hack I know that works is making a freaking single-frame HDR video out of the picture file.
dreamcompiler 6y ago
It's not a gimmick. It's a way to make electronic displays appear closer to what our eyes can see, and it looks great. The whole "HDR photography" thing from the last 10 years that's so overused in real estate photos is not truly high dynamic range; rather it compresses high dynamic range (often captured with multiple exposures) so it will fit onto ordinary (low) dynamic range displays. HDR displays are the real deal. Less compression (or maybe even no compression) is needed because the display can show a much wider range of colors natively. That said, HDR is pointless for the graphical elements of most GUIs. Where it shines is when you're editing photos or movies or viewing them in a window. That window is HDR but outside that window the dynamic range is normal. I saw a link about how Apple is doing this a few weeks ago but can't find it now. It's quite nice as a way to make photos and video really stand out brighter on the screen while letting the GUI elements recede more into the background.
- spideymans 6y ago
  >I saw a link about how Apple is doing this a few weeks ago but can't find it now. I believe this is the article and HN discussion: https://news.ycombinator.com/item?id=25315180 https://news.ycombinator.com/item?id=25315180
  - dreamcompiler 6y ago
    That's it. Thanks!
- saagarjha 6y ago
  https://prolost.com/blog/edr https://prolost.com/blog/edr
- dingaling 6y ago
  > Where it shines is when you're editing photos or movies or viewing them in a window Well it's a step closer but still not enough. Most pro camera RAW files are 14-bit, though many drop down to 12 or 10 bit in high-speed capture modes. There are already monitors that simulate 12-bit output from 10-bit input through internal LUTs but the internal pipeline has been stuck at 10-bit for over a decade. Though it was originally the domain of Quadro cards, it's now available from all discrete GPUs. Technology is still lagging behind what cameras can create let alone what our eyes see.
pzone 6y ago
Pretty much all cinematic media is already produced in HDR and is ideally viewed that way. It’s only compressed to broadcast color at the very end. The experience of HDR is awesome. As soon as the price of the hardware comes down, it will be very popular.
deleted 6y ago
[deleted]
sand500 6y ago
Another part of this is that our TVs are getting brighter or have higher contrast ratios. If we don't allocate more bits for the full range of brightness, we get things like banding in dark scenes. Real about eotfs
lstamour 6y ago
WebKit Blog was one of the earliest resources to show the benefit of producing or previewing web content both for HDR P3 and for standard sRGB output. Best viewed on an OLED phone: https://webkit.org/blog/6682/improving-color-on-the-web/ https://webkit.org/blog/6682/improving-color-on-the-web/ or https://webkit.org/blog-files/color-gamut/comparison.html https://webkit.org/blog-files/color-gamut/comparison.html Recently (2016) YouTube added support for BT.2020 HDR content such as https://youtube.com/playlist?list=PLyqf6gJt7KuGArjMwHmgprtDeY8WDa8YX https://youtube.com/playlist?list=PLyqf6gJt7KuGArjMwHmgprtDe... - you’ll know it’s an HDR video on YouTube by a red symbol that says HDR over the quality control, or if you turn on Stats for Nerds from settings it says bt.2020 in the text somewhere. Even more recently YouTube added live streaming HDR https://blog.youtube/news-and-events/seeing-believing-launching-hdr-live-streams/ https://blog.youtube/news-and-events/seeing-believing-launch... which should come in handy now that PS5 supports HDMI 2.1 and HDR, making the 48” LG OLED TV one of the best gaming monitors ever. (But really expensive and kind of big still...) Unfortunately HDR is backwards compatible, so you have to know your video out and screen are both HDR too. Most flagship OLED cellphones are HDR in P3 colour space if they cost over US$800. Dolby Vision content on Netflix like https://www.netflix.com/title/81017017?s=i&trkid=13747225 https://www.netflix.com/title/81017017?s=i&trkid=13747225 would also show off HDR. I can’t seem to find evidence in the Stats for Nerds box on iOS that it is indeed playing back an HDR copy of the video. You could also try this app, but it didn’t seem to detect my iPhone as Dolby Vision capable when it was: https://apps.apple.com/us/app/dolby-summit/id1528227248 https://apps.apple.com/us/app/dolby-summit/id1528227248 Oh— one last thing, for best colour reproduction, turn off Night Shift, True Tone and turn the brightness all the way up. That will give you the maximum range of colours your screen supports from the most dim blacks to the brightest reds, greens and blues on an OLED display...
- the8472 6y ago
  > BT.2020 HDR Note that BT2020 describes a wider color gamut, not an extended dynamic range. BT2100 is the HDR equivalent.
  - lstamour 6y ago
    Thank you for the correction. https://www.itu.int/pub/R-REP-BT.2390 https://www.itu.int/pub/R-REP-BT.2390 is interesting background material on the subject of HDR. > Recommendation ITU-R BT.2100 – Image parameter values for high dynamic range television for use in production and international programme exchange, specifies parameters for High Dynamic Range television (HDR-TV) signals to be used for programme production and international programme exchange. This Report provides background information on HDR in general, and for the perceptual quantization (PQ) and hybrid log-gamma (HLG) HDR signal parameters specified in the Recommendation. For instance, it confirms what I said elsewhere that 8-bit is mostly fine for consumers to watch HDR: > The non-linearity employed in legacy television systems (Recommendations ITU-R BT.601, BT.709 and BT.2020) is satisfactory in that 10-bit values are usable in production and 8-bit values are usable for delivery to consumers; this is for pictures with approximately 1 000:1 dynamic range[5], i.e. 0.1 to 100 cd/m2. > [Footnote 5]: This definition of dynamic range refers to the luminance ratio between the dimmest and brightest possible pixels presented on the display. However quantization artefacts, known as banding, may be visible, particularly in low lights, at luminance levels substantially brighter than the dimmest pixel. Quantization artefacts may, therefore, limit the “effective” dynamic range that is free from banding. > The PQ HDR system generates content that is optimum for viewing on a reference monitor in a reference viewing environment. The reference monitor would ideally be capable of accurately rendering black levels down to or below 0.005 cd/m2, and highlights up to 10 000 cd/m2. Also, the ideal monitor would be capable of showing the entire colour gamut within the BT.2020 triangle. The viewing environment would ideally be dimly lit, with the area surrounding the monitor being a neutral grey (6 500 degree Kelvin) at a brightness of 5 cd/m2. However, content often must be viewed or produced in environments brighter than the reference condition, and on monitors that cannot display the deepest blacks or brightest highlights that the PQ signal can convey. In these cases the display characteristic needs to be changed in a process often referred to as display mapping (DM). Some of the most interesting sections of BT.2390 are on the advantages of ICTCP or ITP, for short, which is used by Dolby Vision. Apparently due to “constant intensity” if I’m reading this correctly, YCbCr is less preferred and if possible, RGB (in full 4:4:4) is preferred, or one of the other encodings suggested, like ITP or "Y′CC′BCC′RC". https://professional.dolby.com/siteassets/pdfs/ictcp_dolbywhitepaper_v071.pdf https://professional.dolby.com/siteassets/pdfs/ictcp_dolbywh... might also be relevant here.
jayd16 6y ago
Its similar to but not quite the same as the jump from 8 bit color and 16 bit color. White is white and black is black but you'll get more color precision in between. Gradients will have less color banding because of less rounding and color aliasing. Its a bit different because of some of the intricacies of how the new formats are represented. The range is indeed dynamic and that can be exploited to get more precision in a smaller range. However, calling it HDR is (imo almost purposfully) confusing because of HDR photography which has a lot of other concepts as well as hardware vendors promising the moon. TV vendors also like to conflate it with brightness or accuracy which are goals for any TV, HDR or not. Brighter whites and blacker blacks is what you are promised but I think its better to think of it as less crushing (greys getting rounded to white and black).
alkonaut 6y ago
Do I want the color used when staring into the sun in a HDR game to be the background color of notepad? Surely HDR adds headroom “above” normal white rather than just dividing the space between #000 and #fff? I thought HDR screens actually contained brighter leds to create effects like extremely bright areas in movies and games, and not only 10 bits of resolution but normal brightness? In software this isn’t any different obviously, but feels like a kind of gamma correction for choosing where on the output brightness scale “normal white” is?
- akvadrako 6y ago
  There is usually headroom above SDR white for HDR highlights, which is what people usually want. The common scRGB colorspace, often used on windows for games, defines #FFF = 1,1,1 as 200 nits. But it uses floats instead of integers so you can go much higher. You can also go below black = #000.
zeroimpl 6y ago
The 8-bit vs 10-bit aspect is entirely unrelated to the HDR vs SDR aspect. 10-bit is just added precision in your numbers, and ought to be interpreted as adding more decimal places (makes more sense when you imagine the values going from 0-1 instead of 0-255). HDR is indicated as a bit somewhere in metadata to tell the downstream components how to interpret the pixel values. To be extra pedantic, HDR is a bit to indicate how to interpret the brightness (luma) channel. There will be other bits for signaling how to interpret the color channels. Often these things are all done together, which is generally referred to as HDR10.

friedman23 6y ago

> but I suppose it's worth figuring out in the case it becomes commonplace and not another fad like 3D TV. HDR is already here to stay

munchbunny 6y ago

I think it's a big fat "it depends". For example, do GIFs even do HDR? And is there a 10-bits-per-channel specification for PNG's? (I haven't tried to look that up.) Since HDR is a superset of the non-HDR color space, I suspect there will be not that much fuss converting 8-bit to 10-bit, but a whole lot of "magic" involved in converting 10-bit down to 8-bit.

dmitshur 6y ago
PNG supports up to 16-bit depth, and it’s actually a good choice based on an analysis[1] Netflix did in 2018. [1]: https://netflixtechblog.com/enhancing-the-netflix-ui-experience-with-hdr-1e7506ad3e8 https://netflixtechblog.com/enhancing-the-netflix-ui-experie...

the8472 6y ago

Most content will be rendered in sRGB by default. Things will have to opt into WCG/HDR. For CSS specifically you can already opt into WCG via color-gamut, but not into HDR yet. I.e. you can have greener greens but not the whitest white. > which is not quite "stubborn programmer who thinks this is a gimmick" friendly... Perhaps this draft is more readable. https://drafts.csswg.org/css-color-hdr/ https://drafts.csswg.org/css-color-hdr/

ly 6y ago
I’m working on a website with WCG colors right now, and in practice you’re mostly right: Chrome and related browsers only support sRGB, and will thus only show sRGB colors. In Safari you can opt in to use display-p3 for colors in CSS, and it will display those as WCG and everything else still as sRGB. This looks amazing. However, there’s Firefox which only supports sRGB, but then displays everything in WCG completely over saturating every single colored pixel on a website [1]. The only way to get your website to look the way you intended it on Firefox is to make the whole thing black and white. [1] https://www.reddit.com/r/firefox/comments/dloon6/solving_firefoxs_color_saturation_issue_on_wide/ https://www.reddit.com/r/firefox/comments/dloon6/solving_fir...

dmitshur 6y ago

I’d suggest reading https://netflixtechblog.com/enhancing-the-netflix-ui-experience-with-hdr-1e7506ad3e8 https://netflixtechblog.com/enhancing-the-netflix-ui-experie..., it’s quite accessible and gives a good overview of the space.

JohnBooty 6y ago

Here's the best practical demonstration I've found; it's about as well as can be accomplished considering we're talking about looking at pictures of HDR on non-HDR displays. https://prolost.com/blog/edr https://prolost.com/blog/edr It's decidedly not a gimmick. However, it not exactly magic either, and to extent it really relies on the effectiveness of your display's local dimming and maximum brightness. If you're running your display at 50% brightness, then yeah... it's got "more brightness to spare" when it's time to render those extra brighter-than-bright areas. If you're running your display at max 100% brightness already then... well, there's nowhere to go from there. I briefly played around with my 2018 iPad Pro, which has an EDR display. I watched the Apple TV movie "Greyhound" with Tom Hanks. That movie appears to have been shot as something of a demo for HDR rendering. Lots of shots inside the dark, cramped ships, with INTENSELY bright light coming in thru the windows. Watching it on the iPad, the windows were WAY brighter than the rest of the ship interior. But, I could still see everything in the ship interior. It wasn't lost in the shadows. Watching it on my nice Dell IPS monitor, it looked totally different. The portholes were brighter than the ship interior, but not by much. It just looked like a normal movie. It was a very convincing demo. However, perhaps hilariously, I thought it looked better in non-HDR on my Dell. Nonetheless, it was an impressive tech demo.

hatsunearu 6y ago

Hijacking for visiblity: Is there a way of mastering pictures for "real" HDR--not the fake compressed dynamic range crap, but with the right software switches to "turn on" the magic high dynamic range mode through the OS? HDR video specifically has a metadata tag that allows the stream to be correctly viewed on your fancy TV by turning on all the right hardware and software "HDR switch"--like increasing max brightness to the set luminance value in the metadata, etc. For HEIC pictures taken on iPhone, the right switches are turned on in iOS and macOS. Wondering if it's possible to create pictures from my regular sony a7r4 with those metadata tags so it can look cool on fancy displays. I've literally asked everywhere including my workspace Slack (big company) and nobody knows. The only hack I know that works is making a freaking single-frame HDR video out of the picture file.

dreamcompiler 6y ago

It's not a gimmick. It's a way to make electronic displays appear closer to what our eyes can see, and it looks great. The whole "HDR photography" thing from the last 10 years that's so overused in real estate photos is not truly high dynamic range; rather it compresses high dynamic range (often captured with multiple exposures) so it will fit onto ordinary (low) dynamic range displays. HDR displays are the real deal. Less compression (or maybe even no compression) is needed because the display can show a much wider range of colors natively. That said, HDR is pointless for the graphical elements of most GUIs. Where it shines is when you're editing photos or movies or viewing them in a window. That window is HDR but outside that window the dynamic range is normal. I saw a link about how Apple is doing this a few weeks ago but can't find it now. It's quite nice as a way to make photos and video really stand out brighter on the screen while letting the GUI elements recede more into the background.

spideymans 6y ago
>I saw a link about how Apple is doing this a few weeks ago but can't find it now. I believe this is the article and HN discussion: https://news.ycombinator.com/item?id=25315180 https://news.ycombinator.com/item?id=25315180
- dreamcompiler 6y ago
  That's it. Thanks!
saagarjha 6y ago
https://prolost.com/blog/edr https://prolost.com/blog/edr
dingaling 6y ago
> Where it shines is when you're editing photos or movies or viewing them in a window Well it's a step closer but still not enough. Most pro camera RAW files are 14-bit, though many drop down to 12 or 10 bit in high-speed capture modes. There are already monitors that simulate 12-bit output from 10-bit input through internal LUTs but the internal pipeline has been stuck at 10-bit for over a decade. Though it was originally the domain of Quadro cards, it's now available from all discrete GPUs. Technology is still lagging behind what cameras can create let alone what our eyes see.

pzone 6y ago

Pretty much all cinematic media is already produced in HDR and is ideally viewed that way. It’s only compressed to broadcast color at the very end. The experience of HDR is awesome. As soon as the price of the hardware comes down, it will be very popular.

deleted 6y ago

[deleted]

sand500 6y ago

Another part of this is that our TVs are getting brighter or have higher contrast ratios. If we don't allocate more bits for the full range of brightness, we get things like banding in dark scenes. Real about eotfs

lstamour 6y ago

WebKit Blog was one of the earliest resources to show the benefit of producing or previewing web content both for HDR P3 and for standard sRGB output. Best viewed on an OLED phone: https://webkit.org/blog/6682/improving-color-on-the-web/ https://webkit.org/blog/6682/improving-color-on-the-web/ or https://webkit.org/blog-files/color-gamut/comparison.html https://webkit.org/blog-files/color-gamut/comparison.html Recently (2016) YouTube added support for BT.2020 HDR content such as https://youtube.com/playlist?list=PLyqf6gJt7KuGArjMwHmgprtDeY8WDa8YX https://youtube.com/playlist?list=PLyqf6gJt7KuGArjMwHmgprtDe... - you’ll know it’s an HDR video on YouTube by a red symbol that says HDR over the quality control, or if you turn on Stats for Nerds from settings it says bt.2020 in the text somewhere. Even more recently YouTube added live streaming HDR https://blog.youtube/news-and-events/seeing-believing-launching-hdr-live-streams/ https://blog.youtube/news-and-events/seeing-believing-launch... which should come in handy now that PS5 supports HDMI 2.1 and HDR, making the 48” LG OLED TV one of the best gaming monitors ever. (But really expensive and kind of big still...) Unfortunately HDR is backwards compatible, so you have to know your video out and screen are both HDR too. Most flagship OLED cellphones are HDR in P3 colour space if they cost over US$800. Dolby Vision content on Netflix like https://www.netflix.com/title/81017017?s=i&trkid=13747225 https://www.netflix.com/title/81017017?s=i&trkid=13747225 would also show off HDR. I can’t seem to find evidence in the Stats for Nerds box on iOS that it is indeed playing back an HDR copy of the video. You could also try this app, but it didn’t seem to detect my iPhone as Dolby Vision capable when it was: https://apps.apple.com/us/app/dolby-summit/id1528227248 https://apps.apple.com/us/app/dolby-summit/id1528227248 Oh— one last thing, for best colour reproduction, turn off Night Shift, True Tone and turn the brightness all the way up. That will give you the maximum range of colours your screen supports from the most dim blacks to the brightest reds, greens and blues on an OLED display...

the8472 6y ago
> BT.2020 HDR Note that BT2020 describes a wider color gamut, not an extended dynamic range. BT2100 is the HDR equivalent.
- lstamour 6y ago
  Thank you for the correction. https://www.itu.int/pub/R-REP-BT.2390 https://www.itu.int/pub/R-REP-BT.2390 is interesting background material on the subject of HDR. > Recommendation ITU-R BT.2100 – Image parameter values for high dynamic range television for use in production and international programme exchange, specifies parameters for High Dynamic Range television (HDR-TV) signals to be used for programme production and international programme exchange. This Report provides background information on HDR in general, and for the perceptual quantization (PQ) and hybrid log-gamma (HLG) HDR signal parameters specified in the Recommendation. For instance, it confirms what I said elsewhere that 8-bit is mostly fine for consumers to watch HDR: > The non-linearity employed in legacy television systems (Recommendations ITU-R BT.601, BT.709 and BT.2020) is satisfactory in that 10-bit values are usable in production and 8-bit values are usable for delivery to consumers; this is for pictures with approximately 1 000:1 dynamic range[5], i.e. 0.1 to 100 cd/m2. > [Footnote 5]: This definition of dynamic range refers to the luminance ratio between the dimmest and brightest possible pixels presented on the display. However quantization artefacts, known as banding, may be visible, particularly in low lights, at luminance levels substantially brighter than the dimmest pixel. Quantization artefacts may, therefore, limit the “effective” dynamic range that is free from banding. > The PQ HDR system generates content that is optimum for viewing on a reference monitor in a reference viewing environment. The reference monitor would ideally be capable of accurately rendering black levels down to or below 0.005 cd/m2, and highlights up to 10 000 cd/m2. Also, the ideal monitor would be capable of showing the entire colour gamut within the BT.2020 triangle. The viewing environment would ideally be dimly lit, with the area surrounding the monitor being a neutral grey (6 500 degree Kelvin) at a brightness of 5 cd/m2. However, content often must be viewed or produced in environments brighter than the reference condition, and on monitors that cannot display the deepest blacks or brightest highlights that the PQ signal can convey. In these cases the display characteristic needs to be changed in a process often referred to as display mapping (DM). Some of the most interesting sections of BT.2390 are on the advantages of ICTCP or ITP, for short, which is used by Dolby Vision. Apparently due to “constant intensity” if I’m reading this correctly, YCbCr is less preferred and if possible, RGB (in full 4:4:4) is preferred, or one of the other encodings suggested, like ITP or "Y′CC′BCC′RC". https://professional.dolby.com/siteassets/pdfs/ictcp_dolbywhitepaper_v071.pdf https://professional.dolby.com/siteassets/pdfs/ictcp_dolbywh... might also be relevant here.

jayd16 6y ago

Its similar to but not quite the same as the jump from 8 bit color and 16 bit color. White is white and black is black but you'll get more color precision in between. Gradients will have less color banding because of less rounding and color aliasing. Its a bit different because of some of the intricacies of how the new formats are represented. The range is indeed dynamic and that can be exploited to get more precision in a smaller range. However, calling it HDR is (imo almost purposfully) confusing because of HDR photography which has a lot of other concepts as well as hardware vendors promising the moon. TV vendors also like to conflate it with brightness or accuracy which are goals for any TV, HDR or not. Brighter whites and blacker blacks is what you are promised but I think its better to think of it as less crushing (greys getting rounded to white and black).

alkonaut 6y ago

Do I want the color used when staring into the sun in a HDR game to be the background color of notepad? Surely HDR adds headroom “above” normal white rather than just dividing the space between #000 and #fff? I thought HDR screens actually contained brighter leds to create effects like extremely bright areas in movies and games, and not only 10 bits of resolution but normal brightness? In software this isn’t any different obviously, but feels like a kind of gamma correction for choosing where on the output brightness scale “normal white” is?

akvadrako 6y ago
There is usually headroom above SDR white for HDR highlights, which is what people usually want. The common scRGB colorspace, often used on windows for games, defines #FFF = 1,1,1 as 200 nits. But it uses floats instead of integers so you can go much higher. You can also go below black = #000.

zeroimpl 6y ago

The 8-bit vs 10-bit aspect is entirely unrelated to the HDR vs SDR aspect. 10-bit is just added precision in your numbers, and ought to be interpreted as adding more decimal places (makes more sense when you imagine the values going from 0-1 instead of 0-255). HDR is indicated as a bit somewhere in metadata to tell the downstream components how to interpret the pixel values. To be extra pedantic, HDR is a bit to indicate how to interpret the brightness (luma) channel. There will be other bits for signaling how to interpret the color channels. Often these things are all done together, which is generally referred to as HDR10.