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What is HDR, anyway?

lux.camera

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Re: What is HDR, anyway?

#311
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:/…

That Kevin Chen video using Excel was amazing and hilarious. Thanks.

Re: What is HDR, anyway?

#312
post #264

Earlier quoted context omitted.

I'm with you on depth of field, but I don't understand why you think HDR reduces the fidelity of a game. If you have a good display (eg an OLED) then the brights are brighter and simultaneously there is more detail in the blacks. Why do you think that is worse than SDR?

Check out this old post: https://www.realtimerendering.com/blog/thought-for-the-day/ HDR in games would frequently mean clipping highlights and adding bloom. Prior the "HDR" exposure looked rather flat.

That's not what it means since 2016 or so when consumer TVs got support for properly displaying brighter whites and colors.

It definitely adds detail now, and for the last 8-9 years.

Though consumer TVs obviously still fall short of being as bright at peak as the real world. (We'll probably never want our TV to burn out our vision like the sun, though, but probably hitting highs at least in the 1-2000nit range vs the 500-700 that a lot peak at right now would be nice for most uses.

Re: What is HDR, anyway?

#313
post #262
post #243

> Our eyes can see both just fine. This gets to a gaming rant of mine: Our natural vision can handle these things because our eyes scan sections of the scene with constant adjustment (light-level, focus) while our brain is compositing it together into what feels like a single moment. However certain effects in games (i.e. "HDR" and Depth of Field) instead reduce the fidelity of the experience. These features limp alo…

https://www.realtimerendering.com/blog/thought-for-the-day/ It's crazy that post is 15 years old. Like the OP and this post get at, HDR isn't really a good description of what's happening. HDR often means one or more of at least 3 different things (capture, storage, and presentation). It's just the sticker slapped on advertising. Things like lens flares, motion blur, film grain, and shallow depth of field are mimicki…

> Things like lens flares, motion blur, film grain, and shallow depth of field are mimicking cameras and not what being there is like

Ignoring film grain, our vision has all these effects all the same.

Look in front of you and only a single plane will be in focus (and only your fovea produces any sort of legibility). Look towards a bright light and you might get flaring from just your eyes. Stare out the side of a car or train when driving at speed and you'll see motion blur, interrupted only by brief clarity if you intentionally try to follow the motion with your eyes.

Without depth of field simulation, the whole scene is just a flat plane with completely unrealistic clarity, and because it's comparatively small, too much of it is smack center on your fovea. The problem is that these are simulations that do not track your eyes, and make the (mostly valid!) assumption that you're looking, nearby or in front of whatever you're controlling.

Maybe motion blur becomes unneccessary given a high enough resolution and refresh rate, but depth of field either requires actual depth or foveal tracking (which only works for one person). Tasteful application of current techniques is probably better.

> High FPS television can feel cheap while 24fps can feel premium and "filmic."

Ugh. I will never understand the obsession this effect. There is no such thing as a "soap opera effect" as people liek to call it, only a slideshow effect.

The history behind this is purely a series of cost-cutting measures entirely unrelated to the user experience or artistic qualities. 24 fps came to be because audio was slapped onto the film, and was the slowest speed where the audio track was acceptable intelligible, saving costly film paper - the sole priority of the time. Before that, we used to record content at variable frame rates but play it back at 30-40 fps.

We're clinging on to a cost-cutting measure that was a significant compromise from the time of hand cranked film recording.

Re: What is HDR, anyway?

#314
post #262

Earlier quoted context omitted.

https://www.realtimerendering.com/blog/thought-for-the-day/ It's crazy that post is 15 years old. Like the OP and this post get at, HDR isn't really a good description of what's happening. HDR often means one or more of at least 3 different things (capture, storage, and presentation). It's just the sticker slapped on advertising. Things like lens flares, motion blur, film grain, and shallow depth of field are mimicki…

> Things like lens flares, motion blur, film grain, and shallow depth of field are mimicking cameras and not what being there is like Ignoring film grain, our vision has all these effects all the same. Look in front of you and only a single plane will be in focus (and only your fovea produces any sort of legibility). Look towards a bright light and you might get flaring from just your eyes. Stare out the side of a ca…

> Look in front of you and only a single plane will be in focus (and only your fovea produces any sort of legibility). Look towards a bright light and you might get flaring from just your eyes. Stare out the side of a car or train when driving at speed and you'll see motion blur, interrupted only by brief clarity if you intentionally try to follow the motion with your eyes.

The problem is the mismatch between what you’re looking at on the screen and what the in-game camera is looking at. If these were synchronised perfectly it wouldn’t be a problem.

Re: What is HDR, anyway?

#315

Earlier quoted context omitted.

The most egregious example is 3D. Only one thing is in focus, even though the scene is stereoscopic. It makes no sense visually.

Hell yeah, this one of many issues I had with the first Avatar movie. The movie was so filled with cool things to look at but none of it was in focus. 10 minutes in I had had enough and was ready for a more traditional movie experience. Impressive yes, for 10 minutes, then exhausting.

this thread is helping me understand why I always thought 3D movies looked _less_ 3D than 2D movies.

That and after seeing Avatar 1 in 3D, then seeing Avatar 2 in 3D over 10 years later and not really noticing any improvement in the 3D made me declare 3D movies officially dead (though I haven’t done side by side comparisons)

Re: What is HDR, anyway?

#316

Earlier quoted context omitted.

> Things like lens flares, motion blur, film grain, and shallow depth of field are mimicking cameras and not what being there is like Ignoring film grain, our vision has all these effects all the same. Look in front of you and only a single plane will be in focus (and only your fovea produces any sort of legibility). Look towards a bright light and you might get flaring from just your eyes. Stare out the side of a ca…

> Look in front of you and only a single plane will be in focus (and only your fovea produces any sort of legibility). Look towards a bright light and you might get flaring from just your eyes. Stare out the side of a car or train when driving at speed and you'll see motion blur, interrupted only by brief clarity if you intentionally try to follow the motion with your eyes. The problem is the mismatch between what yo…

Indeed - I also mentioned that in the paragraph immediately following.

Re: What is HDR, anyway?

#317

Earlier quoted context omitted.

> Look in front of you and only a single plane will be in focus (and only your fovea produces any sort of legibility). Look towards a bright light and you might get flaring from just your eyes. Stare out the side of a car or train when driving at speed and you'll see motion blur, interrupted only by brief clarity if you intentionally try to follow the motion with your eyes. The problem is the mismatch between what yo…

Indeed - I also mentioned that in the paragraph immediately following.

Derp

Re: What is HDR, anyway?

#318
post #288

Earlier quoted context omitted.

> The sentence “What if I told you that analog photographers captured HDR as far back as 1857?” is explicitly claiming that analog photographers use “HDR” capture, No, it isn't. It's saying they captured HDR scenes. > The result of the juxtaposition is that the article did in fact claim Adams used HDR You can't "use" HDR. It's an adjective, not a noun. > Film’s 12 stops is not really “high” range by HDR standards, an…

Sorry man, you seem really defensive, I didn’t mean to put you on edge. Okay, if you are calling the scenes “HDR” then I’m happy to rescind my critique about Ansel Adams and switch instead to pointing out that “HDR” doesn’t refer to the range of the scene, it refers to the range capability of a digital capture process. I think the point ultimately ends up being the same either way. Hey where is HDR defined as an adje…

You opened this thread arguing that Ansel Adams didn't "use HDR." I linked you to a seminal research paper which argues that he tone mapped HDR content, and goes on to implement a tone mapper based on his approach. This all seems open and shut.

> I’m happy to rescind my critique about Ansel Adams

Great, I'm done.

> and switch instead to pointing out that “HDR” doesn’t refer to the range of the scene

Oh god. Here's the first research paper that popped into my head: https://static.googleusercontent.com/media/hdrplusdata.org/e...

"Surprisingly, daytime shots with high dynamic range may also suffer from lack of light."

"In low light, or in very high dynamic range scenes"

"For high dynamic range scenes we use local tone mapping"

You keep trying to define "HDR" differently than current literature. Not even current— that paper was published in 2016! Hey, maybe HDR meant something different in the 1990s, or maybe it was just ok to use "HDR" as shorthand for when things were less ambiguous. I honestly don't care, and you're only serving to confuse people.

> the aperture can be adjusted on an analog camera to make a scene with any dynamic range fit into the ~12 stops of range the film has, or the ~8 stops of range of paper or an old TV.

You sound nonsensical because you keep using the wrong terms. Going back to your first sentence that made no sense:

> Analog cameras have exposure control and thus can capture any range you want

You keep saying "range" when, from what I can tell, you mean "luminance." Changing a camera's aperture scales the luminance hitting your film or sensor. It does not alter the dynamic range of the scene.

Analog cameras cannot capture any range. By adjusting camera settings or attaching ND filters, you can change the window of luminance values that will fit within the dynamic range of your camera. To say a camera can "capture any range" is like saying, "I can fit that couch through the door, I just have to saw it in half."

> And I’ve used the Reinhard tone mapper in research papers, I’m quite familiar with it and personally know all three authors of that paper. I’ve even written a paper or maybe two on color spaces with one of them.

I'm sorry if correcting you triggers insecurities, but if you're going to make an appeal to authority, please link to your papers instead of hand waving about the people you know.

Re: What is HDR, anyway?

#319

Earlier quoted context omitted.

It still looks like how they say where its way too bright and makes formerly “bright” whites appear even neutral grey surrounding the hdr content. Personally I find it extremely jarring when it is just a frame that is hdr within the overall screen. It is much nicer when the hdr content is full screen. Imo I wish I could just disable partial screen hdr and keep the full screen implementation because it is that distrac…

Out curiosity — I don’t have Instagram to test and this is a perceptual question anyways — if you enable iOS Settings > Accessibility > Display > Reduce White Point (25%) and increase the screen brightness slightly to compensate for the slight dimness; does that reduce or eliminate the ‘jarring’ness?

I’m talking about my macbook and that would be untenable because it needs max brightness on non hdr content in a daylight lit room.

Re: What is HDR, anyway?

#320
post #118

HDR is when you’re watching a dark film at night, looking at the subtle nuances between shades of dark and black in the shadows on the screen, making out the faint contours the film director carefully curated, and the subtitles gently deposit 40W of light into your optical nerves with “♪”.

I actually kind of hate the fact that the subtitles on my (SDR) OLED display never get as bright as some parts of the video itself.
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