7 ms·

Debunking HDR [video]

128 points by plastic3169 1y ago

_wire_ 1y ago
Solid overview of applied color theory for video, so worth watching. As to what was to be debunked, the presentation not only fails to set out a thesis in the introduction, it doesn't even beg a question, so you've got to watch hours to get to the point: SDR and HDR are two measurement systems which when correctly used for most cases (legacy and conventional content) must produce the visual result. The increased fidelity of HDR makes it possible to expand the sensory response and achieve some very realistic new looks that were impossible with SDR, but the significance and value of any look is still up to the creativity of the photographer. This point could be more easily conveyed by this presentation if the author explained in the history of reproduction technology, human visual adaptation exposes a moment by moment contrast window of about 100:1, which is constantly adjusting across time based on average luminance to create an much larger window of perception of billions:1(+) that allows us to operate under the luminance conditions on earth. But until recently, we haven't expected electronic display media to be used in every condition on earth and even if it can work, you don't pick everywhere as your reference environment for system alignment. (+)Regarding difference between numbers such as 100 or billions, don't let your common sense about big or small values phase your thinking about differences: perception is logarithmic; it's the degree of ratios that matter more than the absolute magnitude of the numbers. As a famous acoustics engineer (Paul Klipsch) said about where to focus design optimization of response traits of reproduction systems: "If you can't double it or halve it, don't worry about it."
- strogonoff 1y ago
  Regardless of whether it is HDR or SDR, when processing raw data for display spaces one must throw out 90%+ of information of what was captured by the sensor (which is often a small amount of what was available at the scene already). There can simply be no objectivity, it is always about what you saw and what you want others to see, an inherently creative task.
  - ttoinou 1y ago
    90% really ? What color information get ejected exactly ? For the sensor part are you talking about the fact that the photosites don't cover all the surface ? Or that we only capture a short band of wavelength ? Or that the lens only focuses rays unto specific exact points and make the rest blurry and we loose 3D ?
    - adgjlsfhk1 1y ago
      Presumably they're referring to the fact that most cameras capture ~12-14 bits of brightness vs the 8 that (non-hdr) displays show.
      - ttoinou 1y ago
        Oh that's normal then. There are mandatory steps of dynamic range reduction in the video editing / color grading pipeline (like a compressor in audio production). So the whole information is not lost but the precision / details can be yes. But that's a weird definition, there are so many photons in daylight capture that you could easily say we really need minimum 21 bits per channel minimum (light intensity of sun / light intensity of moon)
        bdavbdav 1y ago
        But that’s not seen at the sensor - at least not at once - look at the sun and then look immediately at the dark sky moon (if it were possible) - the only reason you get the detail on the moon is the aperture in front. You couldn’t see the same detail if they were next to each other. The precision is the most dark in the scene next to the most bright, as opposed to the most dark possible next to the most bright. That’s the difference.
        ttoinou 1y ago
        Hum I can look at a moon croissant and the sun at the same time
- dperfect 1y ago
  It's hard to boil it down to a simple thesis because the problem is complicated. He admits this in the presentation and points to it being part of the problem itself; there are so many technical details that have been met with marketing confusion and misunderstanding that it's almost impossible to adequately explain the problem in a concise way. Here's my takeaway: - It was clearly a mistake to define HDR transfer functions using absolute luminance values. That mistake has created a cascade of additional problems - HDR is not what it was marketed to be: it's not superior in many of the ways people think it is, and in some ways (like efficiency) it's actually worse than SDR - The fundamental problems with HDR formats have resulted in more problems: proprietary formats like Dolby Vision attempting to patch over some of the issues (while being more closed and expensive, yet failing to fully solve the problem), consumer devices that are forced to render things worse than they might be in SDR due to the fact that it's literally impossible to implement the spec 100% (they have to make assumptions that can be very wrong), endless issues with format conversions leading to inaccurate color representation and/or color banding, and lower quality streaming at given bit rates due to HDR's reliance on higher bit depths to achieve the same tonal gradation as SDR - Not only is this a problem for content delivery, but it's also challenging in the content creation phase as filmmakers and studios sometimes misunderstand the technology, changing their process for HDR in a way that makes the situation worse Being somewhat of a film nerd myself and dealing with a lot of this first-hand, I completely agree with the overall sentiment and really hope it can get sorted out in the future with a more pragmatic solution that gives filmmakers the freedom to use modern displays more effectively, while not pretending that they should have control over things like the absolute brightness of a person's TV (when they have no idea what environment it might be in).
  - adrian_b 1y ago
    While HDR has the problems described by you, in practice, whenever possible, I choose the HDR version of a movie over its SDR version. The reason is not HDR itself, but the fact that the HDR movies normally use the BT.2020 color space, while the SDR movies normally use the BT.709 color space. The color spaces based on the limitations of the first color CRT tubes, which are no longer relevant today, i.e. sRGB, BT.709 and the like, are really unacceptable from my point of view, because they cannot reproduce many of the more saturated colors in the red-orange region, which are frequently encountered in nature and in manufactured objects, and which are also located in a region of the color space where human vision is most sensitive. While no cheap monitor can reproduce the full BT.2020, many cheap monitors can reproduce the full DCI-P3 color space, which provides adequate improvements in the red-orange corner over sRGB/BT.709.
jekwoooooe 1y ago
[dead]
empiricus 1y ago
At a minimum we should start from something captured close the reality, and then get creative from that point.. SDR is like black-and-white movies (not quite, but close). We can get creative with it, but can we just see the original natural look? HDR (and the wider color space associated) has a fighting chance to look real, but looking real seems far away from what movie makers are doing.
- jiggawatts 1y ago
  I have a Nikon Z8, which can capture 60 fps 8K footage with (roughly speaking) the equivalent of 1000-nit HDR. The video data rate is something absurd, measured in many gigabits. If you look at the raw footage on an OLED HDR monitor, it's like looking out of a window! You get a feeling that you could just reach out and touch the objects behind the panel. I've seen a few modern HDR productions that have the same "realism aesthetic" and I rather liked it. I've also enjoyed HDR used as a "special effect" with gleaming highlights everywhere. Both styles have their place.
  - nottorp 1y ago
    But the "special effect" should come with a warning label. Tbh so should the excessive messing with colours that's in fashion these days.
naikrovek 1y ago
The switch from 24-bit color to 30-bit color is very similar to the move from 15-bit color on old computers to 16-bit color. You didn’t need new displays to make use of it. It wasn’t suddenly brighter or darker. The change from 15 to 16 bit color was at least visible because the dynamic range of 16-bit color is much lower than 30-bit color, so you could see color banding improve, but it wasn’t some new world of color, like how HDR is sold. Manufacturers want to keep the sales boom that large cheap TVs brought when we moved away from CRTs. That was probably a “golden age” for screen makers. So they went from failing to sell 3D screens to semi-successfully getting everyone to replace their SDR screen with an HDR screen, even though almost no one can see the difference in those color depths when shown with everything else being equal. What really cheeses me on things like this is that TV and monitor manufacturers seem to gate the “blacker blacks” and “whiter whites” behind HDR modes and disable those features for SDR content. That is indefensible.
- ttoinou 1y ago
  As long as the right content was displayed I instantly saw the upgrade to HDR screens (first time I saw one was a smartphone less than 10 years ago I believe), I knew something was new. The same way I could instantly tell when I saw a screen showing a footage with more than 40 fps. And I see constantly on youtube wrongly converted footage from 24 fps to 25 fps, one frame every second jumps / is duplicated
- jakkos 1y ago
  > Manufacturers want to keep the sales boom that large cheap TVs brought when we moved away from CRTs. That was probably a “golden age” for screen makers. IMO the difference between LCD and OLED is massive and "worth buying a new tv" over. I've never tried doing an 8-bit vs 10-bit-per-color "blind" test, but I think I'd be able to see it? > What really cheeses me on things like this is that TV and monitor manufacturers seem to gate the “blacker blacks” and “whiter whites” behind HDR modes and disable those features for SDR content. That is indefensible. This 100%. The hackery I have to regularly perform just to get my "HDR" TV to show an 8-bit-per-color "SDR" signal with it's full range of brightness is maddening.
  - 1y ago
nayuki 1y ago
Unrelated to the video content, the technical delivery of the video is stunningly good. There is no buffering time, and clicking at random points in time on the seek bar gives me a result in about 100 ms. The minimal UI is extremely fast - and because seek happens onmousedown, oftentimes the video is already ready by the time I do onmouseup on the physical button. This is important to me because I like to skip around videos to skim the content to look for anything interesting. Meanwhile, YouTube is incredibly sluggish on my computer, with visible incremental rendering of the page UI, and seeking in a video easily takes 500~1000 ms. It's an embarrassment that the leading video platform, belonging to a multi-billion-dollar company, has a worse user experience than a simple video file with only the web browser's built-in UI controls.
- phonon 1y ago
  More I-frames.
  - CharlesW 1y ago
    Not necessarily more, but importantly the cadence is fixed at one GOP per second — a good (and not-unusual) choice for progressive download delivery.
- echoangle 1y ago
  It’s not that surprising that a massive page would have to compromise quality for scalability (to decrease server load and storage) compared to a smaller page with less visitors.
  - Scaevolus 1y ago
    Most of the perceptual latency on YouTube derives from the massive front-end application, not inherent latency in the backend offering adaptive quality codecs for each video.
- CharlesW 1y ago
  > Unrelated to the video content, the technical delivery of the video is stunningly good. To save readers a "View Source", this is the typical progressive file download user experience with CDNs that support byte-range requests.
ttoinou 1y ago
His previous stuff is so interesting and it's very refreshing to see a Hollywood professional able to dig so deep into those topics and teach us about it https://yedlin.net/NerdyFilmTechStuff/index.html https://yedlin.net/NerdyFilmTechStuff/index.html I think the point that SDR inputs (to a monitor) can be _similar_ to HDR input to monitors that have high dynamic ranges is obvious if you look at the maths involved. Higher dynamic gives you more precision in the information, you can choose to do what you want with it : higher maximum luminosity, better blacks with less noise, more details in the middle etc. Of course we should also see "HDR" as a social movement, a new way to communicate between engineers, manufacturers and consumers, it's not "only" a math conversion formula. I believe we could focus first on comparing SDR and HDR black and white images, to see how higher dynamic range only in the luminosity is in itself very interesting to experience But in the beginning he is saying the images look similar on both monitors. Surely we could find counter examples and that only applies to his cinema stills ? If he can show this is true for all images then indeed he can show that "SDR input to a HDR monitor" is good enough for all human vision. I'm not sure this is true, as I do psychedelic animation I like to use all the gamut of colors I have at my hand and I don't care about representing scenes from the real world, I just want maximum color p0rn to feed my acid brain : 30 bits per pixels surely improve that, as well as wider color gamut / new LEDs wavelengths not used before
- rocqua 1y ago
  As far as I know, most real screens decided to have different display based on HDR or SDR input. Mostly because on HDR they are more willing to do very high brightness for a very small part of the screen. Most displays have the ability to simulate their HDR range on SDR input I believe by dynamically inferring the contrast and seeing if it can punch up small local bright areas.
sansseriff 1y ago
An excellent video. I've admired Yedlin's past work in debunking the need for film cameras over digital when you're going after a 'film look' I wish he shared his code though. Part of the problem is he can't operate like a normal scientist when all the best color grading tools are proprietary. I think it would be really cool to make an open source color grading software that simulates the best film looks. But there isn't enough information on Yedlin's website to exactly reproduce all the research he's done with open source tools.
dcrazy 1y ago
I’m 14 minutes into this 2 hour 15 minute presentation that hinges on precision in terminology, and Yedlin is already making oversimplifications that hamper delivery of his point. First of all, he conflates the actual RGB triplets with the colorspace coordinates they represent. He chooses a floating point representation where each value of the triplet corresponds to a coordinate on the normalized axes of the colorspace, but there are other equally valid encodings of the same coordinates. Integers are very common. Secondly, Rec. 2100 defines more than just a colorspace. A coordinate triple in the Rec. 2100 colorspace does not dictate both luminance and chromaticity. You need to also specify a _transfer function_, of which Rec. 2100 defines two: PQ and HLG. They have different nominal maximum luminance: 10,000 nits for PQ and 1,000 nits for HLG. Without specifying a transfer function, a coordinate triple merely identifies chromaticity. This is true of _all_ color spaces. On the other hand his feet/meters analogy is excellent and I’m going to steal it next time I need to explain colorspace conversion to someone.
- layer8 1y ago
  Continue watching, his overall points are quite valid. The presentation could surely be condensed, but also depends on prior knowledge and familiarity with the concepts.
- wizzledonker 1y ago
  If you watch a little further until about 20 minutes what follows is an explanation of what the primaries represent (described by you as “colorspace coordinates”) along with a reasonable simplification of what a transfer function is, describing it as part of the colorspace. I believe that’s reasonable? He merely explains Rec. 2100 as if using the PQ transfer function is innate. Definitely all seems appropriate and well presented for the target audience.
  - dcrazy 1y ago
    I wasn’t able to resume watching, but if he never describes HLG I would call that a miss for his stated goal. I don’t want to criticize too much, though. Like I said I’ve only watched 15 minutes, and IIRC this is also the guy who convinced a lot of cinematographers that digital was finally good enough.
autobodie 1y ago
I read a whole book about this last year and it made me furious. Well, technically the book was about ACES but it was also about HDR and the problems overlap tremendously. I emphatically agree with this entire video and I will be sharing it widely.
- leguminous 1y ago
  What book was it?
  - autobodie 1y ago
    The Color Management Handbook for Visual Effects Artists by Victor Perez — I do not recommend it.
magicalhippo 1y ago
I just skimmed through parts of the video as I'm about to head to bed, but at least the bits I listened to sounded more like arguing for why 24bit audio isn't necessary for playback, 16bit will do just fine. Back in the days I made ray tracers and such, and going from an internal SDR representation to an internal HDR representation was a complete game changer, especially for multiple reflections. That was a decade or more before any consumer HDR monitors were released, so it was all tonemapped to SDR before displaying. That said, I would really like to see his two monitors display something with really high dynamic range. From the stills I saw in the video, they all seemed quite limited. Anyway, something to watch fully tomorrow, perhaps he addresses this.
- adgjlsfhk1 1y ago
  For pretty much any graphics, you shouldn't be using a capped display space at all. You should be doing all of your math with 32 bit floats (or integers) in a linear color space (wrt photons or human color perception depending on what type of effect you're performing). You should only be converting to a display color space at the end.
- plastic3169 1y ago
  I think he argues more that if 24-bit audio would have been brought to the market like HDR it would have been advertised as being able to be louder. The new stereos would lack the volume control as 24-bit audio would encode absolute volume levels and older formats would play quietly from the new amazing hardware. Songs would be mastered to have more dynamic range changes so that the sound would pop over to loud volumes every now and then. This would be attributed to the higher bit depth of the signal format even though it would be just a different style of producing music. In order to play old songs loud in the new amazing stereo you would need to buy remastered version which would not simply play louder but would overall be quieter to emphasize the volume spikes added in remastering.
  - magicalhippo 1y ago
    Fair point about the absolute scale. It was something that was introduced way later than when I was working on HDR. I think it really should be named HDRA or something, similar to how we have dBA[1], to distinguish it from relative HDR aka "just" HDR. [1]: https://www.engineeringtoolbox.com/decibel-d_59.html https://www.engineeringtoolbox.com/decibel-d_59.html
FrostKiwi 1y ago
Presentation done in fully in Nuke. That's so funny to me. Technical and artistic excellence.
virtualritz 1y ago
Curiously, when I play this back on my Android phone, after entering full screen, I can not exit/close the tab go to another tab. I can also not reach the system launcher any more. I had to kill Chrome via system prefs to make it stop. Seems like this video not only exposes the issues with HDR but also a rather weird bug on Chrome/Android.
IshKebab 1y ago
For those of us that don't have time to randomly watch a 2 hour video, what exactly is being debunked here?

128 points by plastic3169 1y ago

Solid overview of applied color theory for video, so worth watching. As to what was to be debunked, the presentation not only fails to set out a thesis in the introduction, it doesn't even beg a question, so you've got to watch hours to get to the point: SDR and HDR are two measurement systems which when correctly used for most cases (legacy and conventional content) must produce the visual result. The increased fidelity of HDR makes it possible to expand the sensory response and achieve some very realistic new looks that were impossible with SDR, but the significance and value of any look is still up to the creativity of the photographer. This point could be more easily conveyed by this presentation if the author explained in the history of reproduction technology, human visual adaptation exposes a moment by moment contrast window of about 100:1, which is constantly adjusting across time based on average luminance to create an much larger window of perception of billions:1(+) that allows us to operate under the luminance conditions on earth. But until recently, we haven't expected electronic display media to be used in every condition on earth and even if it can work, you don't pick everywhere as your reference environment for system alignment. (+)Regarding difference between numbers such as 100 or billions, don't let your common sense about big or small values phase your thinking about differences: perception is logarithmic; it's the degree of ratios that matter more than the absolute magnitude of the numbers. As a famous acoustics engineer (Paul Klipsch) said about where to focus design optimization of response traits of reproduction systems: "If you can't double it or halve it, don't worry about it."

strogonoff 1y ago
Regardless of whether it is HDR or SDR, when processing raw data for display spaces one must throw out 90%+ of information of what was captured by the sensor (which is often a small amount of what was available at the scene already). There can simply be no objectivity, it is always about what you saw and what you want others to see, an inherently creative task.
- ttoinou 1y ago
  90% really ? What color information get ejected exactly ? For the sensor part are you talking about the fact that the photosites don't cover all the surface ? Or that we only capture a short band of wavelength ? Or that the lens only focuses rays unto specific exact points and make the rest blurry and we loose 3D ?
  - adgjlsfhk1 1y ago
    Presumably they're referring to the fact that most cameras capture ~12-14 bits of brightness vs the 8 that (non-hdr) displays show.
    - ttoinou 1y ago
      Oh that's normal then. There are mandatory steps of dynamic range reduction in the video editing / color grading pipeline (like a compressor in audio production). So the whole information is not lost but the precision / details can be yes. But that's a weird definition, there are so many photons in daylight capture that you could easily say we really need minimum 21 bits per channel minimum (light intensity of sun / light intensity of moon)
      - bdavbdav 1y ago
        But that’s not seen at the sensor - at least not at once - look at the sun and then look immediately at the dark sky moon (if it were possible) - the only reason you get the detail on the moon is the aperture in front. You couldn’t see the same detail if they were next to each other. The precision is the most dark in the scene next to the most bright, as opposed to the most dark possible next to the most bright. That’s the difference.
        ttoinou 1y ago
        Hum I can look at a moon croissant and the sun at the same time
dperfect 1y ago
It's hard to boil it down to a simple thesis because the problem is complicated. He admits this in the presentation and points to it being part of the problem itself; there are so many technical details that have been met with marketing confusion and misunderstanding that it's almost impossible to adequately explain the problem in a concise way. Here's my takeaway: - It was clearly a mistake to define HDR transfer functions using absolute luminance values. That mistake has created a cascade of additional problems - HDR is not what it was marketed to be: it's not superior in many of the ways people think it is, and in some ways (like efficiency) it's actually worse than SDR - The fundamental problems with HDR formats have resulted in more problems: proprietary formats like Dolby Vision attempting to patch over some of the issues (while being more closed and expensive, yet failing to fully solve the problem), consumer devices that are forced to render things worse than they might be in SDR due to the fact that it's literally impossible to implement the spec 100% (they have to make assumptions that can be very wrong), endless issues with format conversions leading to inaccurate color representation and/or color banding, and lower quality streaming at given bit rates due to HDR's reliance on higher bit depths to achieve the same tonal gradation as SDR - Not only is this a problem for content delivery, but it's also challenging in the content creation phase as filmmakers and studios sometimes misunderstand the technology, changing their process for HDR in a way that makes the situation worse Being somewhat of a film nerd myself and dealing with a lot of this first-hand, I completely agree with the overall sentiment and really hope it can get sorted out in the future with a more pragmatic solution that gives filmmakers the freedom to use modern displays more effectively, while not pretending that they should have control over things like the absolute brightness of a person's TV (when they have no idea what environment it might be in).
- adrian_b 1y ago
  While HDR has the problems described by you, in practice, whenever possible, I choose the HDR version of a movie over its SDR version. The reason is not HDR itself, but the fact that the HDR movies normally use the BT.2020 color space, while the SDR movies normally use the BT.709 color space. The color spaces based on the limitations of the first color CRT tubes, which are no longer relevant today, i.e. sRGB, BT.709 and the like, are really unacceptable from my point of view, because they cannot reproduce many of the more saturated colors in the red-orange region, which are frequently encountered in nature and in manufactured objects, and which are also located in a region of the color space where human vision is most sensitive. While no cheap monitor can reproduce the full BT.2020, many cheap monitors can reproduce the full DCI-P3 color space, which provides adequate improvements in the red-orange corner over sRGB/BT.709.

jekwoooooe 1y ago

[dead]

empiricus 1y ago

At a minimum we should start from something captured close the reality, and then get creative from that point.. SDR is like black-and-white movies (not quite, but close). We can get creative with it, but can we just see the original natural look? HDR (and the wider color space associated) has a fighting chance to look real, but looking real seems far away from what movie makers are doing.

jiggawatts 1y ago
I have a Nikon Z8, which can capture 60 fps 8K footage with (roughly speaking) the equivalent of 1000-nit HDR. The video data rate is something absurd, measured in many gigabits. If you look at the raw footage on an OLED HDR monitor, it's like looking out of a window! You get a feeling that you could just reach out and touch the objects behind the panel. I've seen a few modern HDR productions that have the same "realism aesthetic" and I rather liked it. I've also enjoyed HDR used as a "special effect" with gleaming highlights everywhere. Both styles have their place.
- nottorp 1y ago
  But the "special effect" should come with a warning label. Tbh so should the excessive messing with colours that's in fashion these days.

naikrovek 1y ago

The switch from 24-bit color to 30-bit color is very similar to the move from 15-bit color on old computers to 16-bit color. You didn’t need new displays to make use of it. It wasn’t suddenly brighter or darker. The change from 15 to 16 bit color was at least visible because the dynamic range of 16-bit color is much lower than 30-bit color, so you could see color banding improve, but it wasn’t some new world of color, like how HDR is sold. Manufacturers want to keep the sales boom that large cheap TVs brought when we moved away from CRTs. That was probably a “golden age” for screen makers. So they went from failing to sell 3D screens to semi-successfully getting everyone to replace their SDR screen with an HDR screen, even though almost no one can see the difference in those color depths when shown with everything else being equal. What really cheeses me on things like this is that TV and monitor manufacturers seem to gate the “blacker blacks” and “whiter whites” behind HDR modes and disable those features for SDR content. That is indefensible.

ttoinou 1y ago
As long as the right content was displayed I instantly saw the upgrade to HDR screens (first time I saw one was a smartphone less than 10 years ago I believe), I knew something was new. The same way I could instantly tell when I saw a screen showing a footage with more than 40 fps. And I see constantly on youtube wrongly converted footage from 24 fps to 25 fps, one frame every second jumps / is duplicated
jakkos 1y ago
> Manufacturers want to keep the sales boom that large cheap TVs brought when we moved away from CRTs. That was probably a “golden age” for screen makers. IMO the difference between LCD and OLED is massive and "worth buying a new tv" over. I've never tried doing an 8-bit vs 10-bit-per-color "blind" test, but I think I'd be able to see it? > What really cheeses me on things like this is that TV and monitor manufacturers seem to gate the “blacker blacks” and “whiter whites” behind HDR modes and disable those features for SDR content. That is indefensible. This 100%. The hackery I have to regularly perform just to get my "HDR" TV to show an 8-bit-per-color "SDR" signal with it's full range of brightness is maddening.
- 1y ago

nayuki 1y ago

Unrelated to the video content, the technical delivery of the video is stunningly good. There is no buffering time, and clicking at random points in time on the seek bar gives me a result in about 100 ms. The minimal UI is extremely fast - and because seek happens onmousedown, oftentimes the video is already ready by the time I do onmouseup on the physical button. This is important to me because I like to skip around videos to skim the content to look for anything interesting. Meanwhile, YouTube is incredibly sluggish on my computer, with visible incremental rendering of the page UI, and seeking in a video easily takes 500~1000 ms. It's an embarrassment that the leading video platform, belonging to a multi-billion-dollar company, has a worse user experience than a simple video file with only the web browser's built-in UI controls.

phonon 1y ago
More I-frames.
- CharlesW 1y ago
  Not necessarily more, but importantly the cadence is fixed at one GOP per second — a good (and not-unusual) choice for progressive download delivery.
echoangle 1y ago
It’s not that surprising that a massive page would have to compromise quality for scalability (to decrease server load and storage) compared to a smaller page with less visitors.
- Scaevolus 1y ago
  Most of the perceptual latency on YouTube derives from the massive front-end application, not inherent latency in the backend offering adaptive quality codecs for each video.
CharlesW 1y ago
> Unrelated to the video content, the technical delivery of the video is stunningly good. To save readers a "View Source", this is the typical progressive file download user experience with CDNs that support byte-range requests.

ttoinou 1y ago

His previous stuff is so interesting and it's very refreshing to see a Hollywood professional able to dig so deep into those topics and teach us about it https://yedlin.net/NerdyFilmTechStuff/index.html https://yedlin.net/NerdyFilmTechStuff/index.html I think the point that SDR inputs (to a monitor) can be _similar_ to HDR input to monitors that have high dynamic ranges is obvious if you look at the maths involved. Higher dynamic gives you more precision in the information, you can choose to do what you want with it : higher maximum luminosity, better blacks with less noise, more details in the middle etc. Of course we should also see "HDR" as a social movement, a new way to communicate between engineers, manufacturers and consumers, it's not "only" a math conversion formula. I believe we could focus first on comparing SDR and HDR black and white images, to see how higher dynamic range only in the luminosity is in itself very interesting to experience But in the beginning he is saying the images look similar on both monitors. Surely we could find counter examples and that only applies to his cinema stills ? If he can show this is true for all images then indeed he can show that "SDR input to a HDR monitor" is good enough for all human vision. I'm not sure this is true, as I do psychedelic animation I like to use all the gamut of colors I have at my hand and I don't care about representing scenes from the real world, I just want maximum color p0rn to feed my acid brain : 30 bits per pixels surely improve that, as well as wider color gamut / new LEDs wavelengths not used before

rocqua 1y ago
As far as I know, most real screens decided to have different display based on HDR or SDR input. Mostly because on HDR they are more willing to do very high brightness for a very small part of the screen. Most displays have the ability to simulate their HDR range on SDR input I believe by dynamically inferring the contrast and seeing if it can punch up small local bright areas.

sansseriff 1y ago

An excellent video. I've admired Yedlin's past work in debunking the need for film cameras over digital when you're going after a 'film look' I wish he shared his code though. Part of the problem is he can't operate like a normal scientist when all the best color grading tools are proprietary. I think it would be really cool to make an open source color grading software that simulates the best film looks. But there isn't enough information on Yedlin's website to exactly reproduce all the research he's done with open source tools.

dcrazy 1y ago

I’m 14 minutes into this 2 hour 15 minute presentation that hinges on precision in terminology, and Yedlin is already making oversimplifications that hamper delivery of his point. First of all, he conflates the actual RGB triplets with the colorspace coordinates they represent. He chooses a floating point representation where each value of the triplet corresponds to a coordinate on the normalized axes of the colorspace, but there are other equally valid encodings of the same coordinates. Integers are very common. Secondly, Rec. 2100 defines more than just a colorspace. A coordinate triple in the Rec. 2100 colorspace does not dictate both luminance and chromaticity. You need to also specify a _transfer function_, of which Rec. 2100 defines two: PQ and HLG. They have different nominal maximum luminance: 10,000 nits for PQ and 1,000 nits for HLG. Without specifying a transfer function, a coordinate triple merely identifies chromaticity. This is true of _all_ color spaces. On the other hand his feet/meters analogy is excellent and I’m going to steal it next time I need to explain colorspace conversion to someone.

layer8 1y ago
Continue watching, his overall points are quite valid. The presentation could surely be condensed, but also depends on prior knowledge and familiarity with the concepts.
wizzledonker 1y ago
If you watch a little further until about 20 minutes what follows is an explanation of what the primaries represent (described by you as “colorspace coordinates”) along with a reasonable simplification of what a transfer function is, describing it as part of the colorspace. I believe that’s reasonable? He merely explains Rec. 2100 as if using the PQ transfer function is innate. Definitely all seems appropriate and well presented for the target audience.
- dcrazy 1y ago
  I wasn’t able to resume watching, but if he never describes HLG I would call that a miss for his stated goal. I don’t want to criticize too much, though. Like I said I’ve only watched 15 minutes, and IIRC this is also the guy who convinced a lot of cinematographers that digital was finally good enough.

autobodie 1y ago

I read a whole book about this last year and it made me furious. Well, technically the book was about ACES but it was also about HDR and the problems overlap tremendously. I emphatically agree with this entire video and I will be sharing it widely.

leguminous 1y ago
What book was it?
- autobodie 1y ago
  The Color Management Handbook for Visual Effects Artists by Victor Perez — I do not recommend it.

magicalhippo 1y ago

I just skimmed through parts of the video as I'm about to head to bed, but at least the bits I listened to sounded more like arguing for why 24bit audio isn't necessary for playback, 16bit will do just fine. Back in the days I made ray tracers and such, and going from an internal SDR representation to an internal HDR representation was a complete game changer, especially for multiple reflections. That was a decade or more before any consumer HDR monitors were released, so it was all tonemapped to SDR before displaying. That said, I would really like to see his two monitors display something with really high dynamic range. From the stills I saw in the video, they all seemed quite limited. Anyway, something to watch fully tomorrow, perhaps he addresses this.

adgjlsfhk1 1y ago
For pretty much any graphics, you shouldn't be using a capped display space at all. You should be doing all of your math with 32 bit floats (or integers) in a linear color space (wrt photons or human color perception depending on what type of effect you're performing). You should only be converting to a display color space at the end.
plastic3169 1y ago
I think he argues more that if 24-bit audio would have been brought to the market like HDR it would have been advertised as being able to be louder. The new stereos would lack the volume control as 24-bit audio would encode absolute volume levels and older formats would play quietly from the new amazing hardware. Songs would be mastered to have more dynamic range changes so that the sound would pop over to loud volumes every now and then. This would be attributed to the higher bit depth of the signal format even though it would be just a different style of producing music. In order to play old songs loud in the new amazing stereo you would need to buy remastered version which would not simply play louder but would overall be quieter to emphasize the volume spikes added in remastering.
- magicalhippo 1y ago
  Fair point about the absolute scale. It was something that was introduced way later than when I was working on HDR. I think it really should be named HDRA or something, similar to how we have dBA[1], to distinguish it from relative HDR aka "just" HDR. [1]: https://www.engineeringtoolbox.com/decibel-d_59.html https://www.engineeringtoolbox.com/decibel-d_59.html

FrostKiwi 1y ago

Presentation done in fully in Nuke. That's so funny to me. Technical and artistic excellence.

virtualritz 1y ago

Curiously, when I play this back on my Android phone, after entering full screen, I can not exit/close the tab go to another tab. I can also not reach the system launcher any more. I had to kill Chrome via system prefs to make it stop. Seems like this video not only exposes the issues with HDR but also a rather weird bug on Chrome/Android.

IshKebab 1y ago

For those of us that don't have time to randomly watch a 2 hour video, what exactly is being debunked here?