Comment by _wire_
Comment by _wire_ 5 days 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."
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).