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What is HDR, anyway?

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Re: What is HDR, anyway?

#71

Post by the_af »

CarVac wrote: post #3

HDR on displays is actually largely uncomfortable for me. They should reserve the brightest HDR whites for things like the sun itself and caustics, not white walls in indoor photos. As for tone mapping, I think the examples they show tend way too much towards flat low-local-contrast for my tastes.

There's a pretty good video on YouTube (more than one, actually) that explains how careless use of HDR in modern cinema is destroying the look and feel of cinema we used to like.

Everything is flattened, contrast is eliminated, lights that should be "burned white" for a cinematic feel are brought back to "reasonable" brightness with HDR, really deep blacks are turned into flat greys, etc. The end result is the flat and washed out look of movies like Wicked. It's often correlated to CGI-heavy movies, but in reality it's starting to affect every movie.

Re: What is HDR, anyway?

#72

Post by asafira »

I did my PhD in Atomic, Molecular, and Optical (AMO) physics, and despite "optical" being part of that I realized midway that I didn't know enough about how regular cameras worked!

It didn't take very long to learn, and it turned out to be extremely important in the work I did during the early days at Waymo and later at Motional.

I wanted to pass along this fun video from several years ago that discusses HDR: https://www.youtube.com/watch?v=bkQJdaGGVM8 . It's short and fun, I recommend it to all HN readers.

Separately, if you want a more serious introduction to digital photography, I recommend the lectures by Marc Levoy from his Stanford course: https://www.youtube.com/watch?v=y7HrM-fk_Rc&list=PL8ungNrvUY... . I believe he runs his own group at Adobe now after leading a successful effort at Google making their pixel cameras the best in the industry for a couple of years. (And then everyone more-or-less caught up, just like with most tech improvements in the history of smartphones).

Re: What is HDR, anyway?

#73

Post by colechristensen »

dmitshur wrote: post #67
aidenn0 wrote: post #62

> A big problem is that it costs the TV, Film, and Photography industries billions of dollars (and a bajillion hours of work) to upgrade their infrastructure. For context, it took well over a decade for HDTV to reach critical mass. This is also true for consumers. I don't own a single 4k or HDR display. I probably won't own an HDR display until my TV dies, and I probably won't own a 4k display until I replace my work…

To demonstrate some contrast (heh) with another data point from someone closer to the other extreme, I’ve owned a very HDR-capable monitor (the Apple Pro Display XDR) since 2020, so that’s 5 years now. Content that takes full advantage of it is still rare, but it’s getting better slowly over time.

I have a screen which is "HDR" but what that means is when you turn the feature on it just makes everything more muted, it doesn't actually have any more dynamic range. When you turn HDR on for a game it basically just makes most things more muddy grey.

I also have a screen which has a huge gamut and blows out colors in a really nice way (a bit like the aftereffects of hallucinogens, it has colors other screens just don't) and you don't have to touch any settings.

My OLED TV has HDR and it actually seems like HDR content makes a difference while regular content is still "correct".

Re: What is HDR, anyway?

#74

Post by dheera »

sandofsky wrote: post #21
gyomu wrote: post #5

As a photographer, I get the appeal of (this new incarnation of) HDR content, but the practical reality is that the photos I see posted in my feeds go from making my display looking normal to having photos searing my retinas, while other content that was uniform white a second prior now looks dull gray. It's late night here so I was reading this article in dark mode, at a low display brightness - and when I got to th…

While it isn't touched on in the post, I think the issue with feeds is that platforms like Instagram have no interest in moderating HDR. For context: YouTube automatically edits the volume of videos that have an average loudness beyond a certain threshold. I think the solution for HDR is similar penalization based on log luminance or some other reasonable metric. I don't see this happening on Instagram any time soon,…

> because bad HDR likely makes view counts go up

Another related parallel trend recently is that bad AI images get very high view and like counts, so much so that I've lost a lot of motivation for doing real photography because the platforms cease to show them to anyone, even my own followers.

Re: What is HDR, anyway?

#75

Post by hatsunearu »

Is there any workflow that can output HDR photos (like the real HDR kind, with metadata to tell the display to go into HDR mode) for photos shot with a mirrorless and not an iPhone?

Re: What is HDR, anyway?

#76

Post by colechristensen »

reaperducer wrote: post #70
aidenn0 wrote: post #62

> A big problem is that it costs the TV, Film, and Photography industries billions of dollars (and a bajillion hours of work) to upgrade their infrastructure. For context, it took well over a decade for HDTV to reach critical mass. This is also true for consumers. I don't own a single 4k or HDR display. I probably won't own an HDR display until my TV dies, and I probably won't own a 4k display until I replace my work…

This is also true for consumers. I don't own a single 4k or HDR display. I probably won't own an HDR display until my TV dies, and I probably won't own a 4k display until I replace my work screen, at which point I'll also replace one of my home screens so I can remote into it without scaling. People in the HN echo chamber over-estimate hardware adoption rates. For example, there are millions of people who went straig…

>there are millions of people who went straight from CDs to streaming, without hitting the iPod era

Who?

There was about a decade there where everyone who had the slightest interest in music had an mp3 player of some kind, at least in the 15-30 age bracket.

Re: What is HDR, anyway?

#77

Post by kllrnohj »

eschatology wrote: post #66
kllrnohj wrote: post #52

Earlier quoted context omitted.

> You know the 0-10 brightness slider you have to pick at the start of a game? Imagine setting it to 0 and still being able to spot the faint dark spot. The dynamic range of things you can see is so much expanded. Note that HDR only actually changes how bright things can get. There's zero difference in the dark regions. This is made confusing because HDR video marketing often claims it does, but it doesn't actually.…

My understanding is that on the darker scenes (say, 0 to 5 in the brightness slider example), there is difference in luminance value with HDR but not SDR, so there is increased contrast and detail. This matches my experience; 0 to 5 look identically black if I turn off HDR

You may have a monitor that only enables local dimming zones when fed an HDR signal but not when fed an SDR one, but that would be unusual and certainly not required. And likely something you could change in your monitors controls. On things like an OLED, though, there's no difference in the darks. You'd see a difference between 8bit and 10bit potentially depending on what "0 to 5" means, but 10-bit SDR is absolutely a thing (it predates HDR even)

But like if you can't see a difference between 0 to 5 in a test pattern like this https://images.app.goo.gl/WY3FhCB1okaRANc28 in SDR but you can in HDR then that just means your SDR factory calibration is bad, or you've fiddled with settings that broke it.

Re: What is HDR, anyway?

#78

Post by baq »

the__alchemist wrote: post #4

So, HN, are HDR monitors worth it? I remember ~10 years ago delaying my monitor purchase for the HDR one that was right around the corner, but never (in my purchasing scope) became available. Time for another look? The utility of HDR (as described in the article) is without question. It's amazing looking at an outdoors (or indoors with windows) scene with your Mk-1 eyeballs, then taking a photo and looking at it on a…

I've had an OLED TV since 2017 and the answer is a resounding yes... if you get an OLED and use it for movies or full screen gaming. Anything else is basically pointless.

For desktop work, don't bother unless your work involves HDR content.

Re: What is HDR, anyway?

#79

Post by aidenn0 »

colechristensen wrote: post #76
reaperducer wrote: post #70

Earlier quoted context omitted.

This is also true for consumers. I don't own a single 4k or HDR display. I probably won't own an HDR display until my TV dies, and I probably won't own a 4k display until I replace my work screen, at which point I'll also replace one of my home screens so I can remote into it without scaling. People in the HN echo chamber over-estimate hardware adoption rates. For example, there are millions of people who went straig…

>there are millions of people who went straight from CDs to streaming, without hitting the iPod era Who? There was about a decade there where everyone who had the slightest interest in music had an mp3 player of some kind, at least in the 15-30 age bracket.

I don't know if I count, but I never owned a dedicated MP3 player[1], I listened to MP3s on my computer, but used CDs and cassettes while on the move, until I got an android phone that had enough storage to put my music collection on.

1: Well my car would play MP3s burned to CDs in its CD player; not sure if that counts.

Re: What is HDR, anyway?

#80

Post by cornstalks »

skhameneh wrote: post #42
cornstalks wrote: post #17

Earlier quoted context omitted.

No. HDR video (and images) don't use floating point encoding. They generally use a higher bit depth (10 bits or more vs 8 bits) to reduce banding and different transfer characteristics (i.e. PQ or HLG vs sRGB or BT.709), in addition to different YCbCr matrices and mastering metadata. And no, it's not necessarily absolute luminance. PQ is absolute, HLG is not.

Isn’t HLG using floating point(s)? Also DCI-P3 should fit in here somewhere, as it seems to be the most standardized color space for HDR. I would share more insight, if I had it. I thought I understood color profiles well, but I have encountered some challenges when trying to display in one, edit in another, and print “correctly”. And every device seems to treat color profiles a little bit differently.

You can read the actual HLG spec here: https://www.arib.or.jp/english/html/overview/doc/2-STD-B67v2...

The math uses real numbers but table 2-4 ("Digital representation") discusses how the signal is quantized to/from analog and digital. The signal is quantized to integers.

This same quantization process is done for sRGB, BT.709, BT.2020, etc. so it's not unique to HLG. It's just how digital images/video are stored.

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