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What is HDR, anyway?

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Re: What is HDR, anyway?

#221

Post by brcmthrowaway »

asafira wrote: post #72

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:/…

Pixel camera hardware or software? Isnt there only one vendor for sensors - Sony?

Re: What is HDR, anyway?

#222

Post by tshaddox »

arghwhat wrote: post #214
dahart wrote: post #168

Earlier quoted context omitted.

This! Yes I think you’re absolutely right. The term “HDR” is in part kind of an artifact of how digital image formats evolved, and it kind of only makes sense relative to a time when the most popular image formats and most common displays were not very sophisticated about colors. That said, there is one important part that is often lost. One of the ideas behind HDR, sometimes, is to capture absolute values in physica…

Absolute is also a funny size. From the perspective of human visual perception, an absolute brightness only matters if the entire viewing environment is also controlled to the same absolute values. Visual perception is highly contextual, and we are not only seeing the screen. It's not fun being unable to watch dark scenes during the day or evening in a living room, nor is vaporizing your retinas if the ambient enviro…

Indeed. For a movie scene depicting the sky including the Sun, you probably wouldn't want your TV to achieve the same brightness as the Sun. You might want your TV to become significantly brighter than the rest of the scenes, to achieve an effect something like the Sun catching your eye.

Of course, the same thing goes for audio in movies. You probably want a gunshot or explosion to sound loud and even be slightly shocking, but you probably don't want it to be as loud as a real gunshot or explosion would be from the depicted distance.

The difference is that for 3+ decades the dynamic range of ubiquitous audio formats (like 16 bit PCM in audio CDs and DVDs) has provided far more dynamic range than is comfortably usable in normal listening environments. So we're very familiar with audio being mastered with a much smaller dynamic range than the medium supports.

Re: What is HDR, anyway?

#223

Post by dahart »

munificent wrote: post #213
dahart wrote: post #185

Earlier quoted context omitted.

HDR is not referring to the scene’s range, and it doesn’t apply to film. It’s referring superficially but specifically to a digital process that improves on 8 bits/channel RGB images. And one of the original intents behind HDR was to capture pixels in absolute physical measurements like radiance, to enable a variety of post-processing workflows that are not available to film.

"High dynamic range" is a phrase that is much older than tone mapping. I see uses of "dynamic range" going back to the 1920s and "high dynamic range" to the 1940s: https://books.google.com/ngrams/graph?content=dynamic+range%... You might argue that "HDR" the abbreviation refers to using tone mapping to approximate rendering high dynamic range imagery on lower dynamic range displays. But even then, the sentence in que…

> But even then, the sentence in question doesn’t use the abbreviation

Yes it does. Why are you still looking at a different sentence than the one I quoted??

HDR in this context isn’t referring to just any dynamic range. If it was, then it would be so vague as to be meaningless.

Tone mapping is closely related to HDR and very often used, but is not necessary and does not define HDR. To me it seems like your argument is straw man. Photographers have never broadly used the term “high dynamic range” as a phrase, nor the acronym “HDR” before it showed up in computer apps like hdrView, Photoshop, and iPhone camera.

Re: What is HDR, anyway?

#224

Post by Suppafly »

altairprime wrote: post #169
Suppafly wrote: post #146

Earlier quoted context omitted.

Nothing you're written disproves that no one wants it, if anything the fact that nothing really supports it implies that it's not a valuable feature that people are clamoring for.

Given how popular it is in modern console AAA gaming, which many people do play on PCs, one can reasonably expect that any studio desiring to target high contrast gaming — a valuable niche for stealth games, where a bright torch should absolutely stand out brightly against the darkest shadows, as well as star exploration and anything with landscapes or specular highlights — would like to be targeting HDR on PC, if on…

>Given how popular it is in modern console AAA gaming

What are some of the games where it's necessary?

Re: What is HDR, anyway?

#225

Post by xienze »

simoncion wrote: post #110
NBJack wrote: post #36

Earlier quoted context omitted.

HDR is really hard to get right apparently. It seems to get worse in video games too. I'm a huge fan of Helldivers 2, but playing the game in HDR gives me a headache: the muzzle flash of weapons at high RPMs on a screen that goes to 240hz is basically a continuous flashbang for my eyes. For a while, No Mans' Sky in HDR mode was basically the color saturation of every planet dialed up to 11. The only game I've enjoyed…

For a year or two after it launched, The Division 2 was a really, really good example of HDR done right. The game had (has?) a day/night cycle, and it had a really good control of the brightness throughout the day. More importantly, it made very good use of the wide color gamut available to it. I stopped playing that game for several years, and when I went back to it, the color and brightness had been wrecked to all…

> I have heard that it's received wisdom that gamers complain that HDR modes are "too dark", so perhaps that's part of why they ruined their game's renderer.

A lot of people have cheap panels that claim HDR support (read: can display an HDR signal) but have garbage color space coverage, no local dimming, etc. and to them, HDR ends up looking muted.

Re: What is HDR, anyway?

#226

Post by squidsoup »

As a photographer, one of the things that draws me to the work of artists like Bill Brandt and Daido Moriyama is their use of low dynamic range, and high contrast. I rarely see an HDR image that is aesthetically interesting.

Re: What is HDR, anyway?

#227

Post by jiggawatts »

the_af wrote: post #71
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 a…

The washed out grey thing was an error that became a style!

Because HDR wasn’t natively supported on most displays and software, for a long time it was just “hacked in there” by squashing the larger dynamic range into a smaller one using a mathematical transform, usually a log function. When viewed without the inverse transform this looks horribly grey and unsaturated.

Directors and editors would see this aesthetic day in, day out, with the final color grade applied only after a long review process.

Some of them got used to it and even liking it, and now here we are: horribly washed out movies made to look like that on purpose.

Re: What is HDR, anyway?

#228

Post by frollogaston »

kllrnohj wrote: post #211
frollogaston wrote: post #180

Earlier quoted context omitted.

"On both Android & iOS/MacOS it's not that HDR is ignoring your screen brightness, but rather the brightness slider is controlling the SDR range and then yes HDR can exceed that" Doesn't this mean HDR is ignoring my brightness setting? Looking at the Mac color profiles, the default HDR has some fixed max brightness regardless of the brightness slider. And it's very bright, 1600 nits vs the SDR max of 600 nits. At lea…

> Doesn't this mean HDR is ignoring my brightness setting? Not exactly because it is still being scaled by your brightness setting. As in, start playing an HDR video and then mess with the brightness slider. You will still see the HDR content getting dimmer/brighter. It's easier to think about in Apple's EDR terms. 0.0-1.0 is the SDR range, and the brightness slider is changing what the nit value is of "1.0" - is it…

Ah, just tested with https://github.com/dtinth/superwhite and you're correct. I remember it not even scaling with the brightness, but guess I was wrong.

Re: What is HDR, anyway?

#229

Post by [deleted] »

mightysashiman wrote: post #216
redox99 wrote: post #210

Earlier quoted context omitted.

You would need a very strong light surrounded by a darkish environent. I don't see a point in "HDR Paper" if you need to place it under a special light.

usecase: a photo exhibition that wants to show pictures in HDR = An HDR print setup (i.e. paper + appropriately controlled lighting). Haven't you ever been to a photo exhibition ?

[deleted]

Re: What is HDR, anyway?

#230

Post by BlueTemplar »

tshaddox wrote: post #219
arghwhat wrote: post #153

Earlier quoted context omitted.

Arguably, even considering HDR a distinct thing is itself weird an inaccurate. All mediums have a range, and they've never all matched. Sometimes we've tried to calibrate things to match, but anyone watching SDR content for the past many years probably didn't do so on a color-calibrated and brightness calibrated screen - that wouldn't allow you to have a brightness slider. HDR on monitors is about communicating conte…

The term "HDR" arguably makes more sense for the effect achieved by tone mapping multiple exposures of the same subject onto a "normal" (e.g. SRGB) display. In this case, the "high" in "HDR" just means "from a source with higher dynamic range than the display."

Remember "wide gamut" screens ?

This is part of 'HDR' standards too...

And it's quite annoying that 'HDR' (and which specific one ?) is treated as just being 'on' or 'off' even for power users...

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