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What is HDR, anyway?

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Re: What is HDR, anyway?

#191

Post by LinAGKar »

kllrnohj wrote: post #50
beachwood23 wrote: post #18

Earlier quoted context omitted.

Completely agree. To me, HDR feels like the system is ignoring my screen brightness settings. I set my screen brightness to a certain level for a reason . Please don’t just arbitrarily turn up the brightness! There is no good way to disable HDR on photos for iPhone, either. Sure, you can turn off the HDR on photos on your iphone. But then, when you cast to a different display, the TV tries to display the photos in HD…

> To me, HDR feels like the system is ignoring my screen brightness settings. 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, that's the singular purpose of HDR to be honest. All the other purported benefits of HDR are at best just about HDR video profiles and at worst just nonsense bullsh…

>HDR can exceed that

It's not just the HDR content that gets brighter, but SDR content too. When I test it in Chrome on Android, if an HDR image shows up on screen the phone start overriding the brightness slider completely and making everything brighter, including the phone's system UI.

>The only thing HDR actually does is allow for brighter colors vs. SDR.

Not just brighter, but also darker, so it can preserve detail in dark areas rather than crushing them.

Re: What is HDR, anyway?

#192

Post by altairprime »

dahart wrote: post #185
munificent wrote: post #179

Earlier quoted context omitted.

Yes, Ansel Adams was using a camera to capture a scene that had high dynamic range. I don't see the confusion here.

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.

The digital process of tonemapping, aka. 'what Apple calls Smart HDR processing of SDR photos to increase perceptual dynamic range', can be applied to images of any number of channels of any bit depth — though, if you want to tonemap a HyperCard dithered black-and-white image, you'll probably have to decompile the dithering as part of creating the gradient map. Neither RGB nor 8-bit are necessary to make tonemapping a valuable step in image processing.

Re: What is HDR, anyway?

#193

Post by labadal »

Back in university I implemented a shoddy HDR for my phone camera.

The hardest part of it, by far, was taking hundreds upon hundreds of pictures of a blank piece of paper in different lighting conditions with different settings.

Re: What is HDR, anyway?

#194

Post by FireBeyond »

willquack wrote: post #83
mxfh wrote: post #22

Does anyone else find the hubris in the first paragraph writing as off-putting as I do? "we finally explain what HDR actually means" Then spends 2/3rds of the article on a tone mapping expedition, only to not address the elephant in the room, that is the almost complete absence of predictable color management in consumer-grade digital environments. UIs are hardly ever tested in HDR: I don't want my subtitles to burn…

> That brightness abuse by content I predict HDR content on the web will eventually be disabled or mitigated on popular browsers similarly to how auto-playing audio content is no longer allowed [1] Spammers and advertisers haven't caught on yet to how abusively attention grabbing eye-searingly bright HDR content can be, but any day now they will and it'll be everywhere. 1. https://hacks.mozilla.org/2019/02/firefox-66…

They haven't, but influencers certainly have, I get regular still images which are rendered as a video to get the HDR brightness boost in Instagram, etc.

Re: What is HDR, anyway?

#195

Post by pavlov »

dahart wrote: post #189
pavlov wrote: post #186

Earlier quoted context omitted.

That’s a strange claim because the first digital HDR capture devices were film scanners (for example the Cineon equipment used by the motion picture industry in the 1990s). Film provided a higher dynamic range than digital sensors, and professionals wanted to capture that for image editing. Sure, it wasn’t terribly deep HDR by today’s standards. Cineon used 10 bits per channel with the white point at coding value 685…

They didn’t call that “HDR” at the time, and it wasn’t based on the idea of recording radiance or other absolute physical units. I’m certain physicists had high range digital cameras before Cineon, and they were working in absolute physical metrics. That would be a stronger example. You bring up an important point that is completely lost in the HDR discussion: this is about color resolution at least as much as it’s a…

It certainly was called HDR when those Cineon files were processed in a linear light workflow. And film was the only capture source available that could provide sufficient dynamic range, so IMO that makes it “HDR”.

But I agree that the term is such a wide umbrella that almost anything qualifies. Fifteen years ago you could do a bit of superwhite glows and tone mapping on 8-bpc and people called that look HDR.

Re: What is HDR, anyway?

#196

Post by levidos »

dahart wrote: post #123

It seems like a mistake to lump HDR capture, HDR formats and HDR display together, these are very different things. The claim that Ansel Adams used HDR is super likely to cause confusion, and isn’t particularly accurate. We’ve had HDR formats and HDR capture and edit workflows since long before HDR displays. The big benefit of HDR capture & formats is that your “negative” doesn’t clip super bright colors and doesn’t…

Is there a difference in capturing in HDR vs RAW?

Re: What is HDR, anyway?

#197

Post by altairprime »

dahart wrote: post #189
pavlov wrote: post #186

Earlier quoted context omitted.

That’s a strange claim because the first digital HDR capture devices were film scanners (for example the Cineon equipment used by the motion picture industry in the 1990s). Film provided a higher dynamic range than digital sensors, and professionals wanted to capture that for image editing. Sure, it wasn’t terribly deep HDR by today’s standards. Cineon used 10 bits per channel with the white point at coding value 685…

They didn’t call that “HDR” at the time, and it wasn’t based on the idea of recording radiance or other absolute physical units. I’m certain physicists had high range digital cameras before Cineon, and they were working in absolute physical metrics. That would be a stronger example. You bring up an important point that is completely lost in the HDR discussion: this is about color resolution at least as much as it’s a…

It was called "extended dynamic range" by ILM when they published the OpenEXR spec (2003):

> OpenEXR (www.openexr.net), its previously proprietary extended dynamic range image file format, to the open source community

https://web.archive.org/web/20170721234341/http://www.openex...

And "larger dynamic range" by Rea & Jeffrey (1990):

> With γ = 1 there is equal brightness resolution over the entire unsaturated image at the expense of a larger dynamic range within a given image. Finally, the automatic gain control, AGC, was disabled so that the input/output relation would be constant over the full range of scene luminances.

https://doi.org/10.1080/00994480.1990.10747942

I'm not sure when everyone settled on "high" rather than "large" or "extended", but certainly 'adjective dynamic range' is near-universal.

Re: What is HDR, anyway?

#198

Post by dahart »

altairprime wrote: post #192
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.

The digital process of tonemapping, aka. 'what Apple calls Smart HDR processing of SDR photos to increase perceptual dynamic range', can be applied to images of any number of channels of any bit depth — though, if you want to tonemap a HyperCard dithered black-and-white image, you'll probably have to decompile the dithering as part of creating the gradient map. Neither RGB nor 8-bit are necessary to make tonemapping…

That’s true, and it’s why tonemapping is distinct from HDR. If you follow the link from @xeonmc’s comment and read the comments, the discussion centers on the conflation of tonemapping and HDR.

https://news.ycombinator.com/item?id=43987923

That said, the entire reason that tonemapping is a thing, and the primary focus of the tonemapping literature, is to solve the problem of squeezing images with very wide ranges into narrow display ranges like print and non-HDR displays, and to achieve a natural look that mirrors human perception of wide ranges. Tonemapping might be technically independent of HDR, but they did co-evolve, and that’s part of the history.

Re: What is HDR, anyway?

#199

Post by hbn »

scraptor wrote: post #106
tart-lemonade wrote: post #102

Earlier quoted context omitted.

> YouTube automatically edits the volume of videos that have an average loudness beyond a certain threshold. For anyone else who was confused by this, it seems to be a client-side audio compressor feature (not a server-side adjustment) labeled as "Stable Volume". On the web, it's toggleable via the player settings menu. https://support.google.com/youtube/answer/14106294 I can't find exactly when it appeared but the e…

The client side toggle might be new since 2024 but the volume normalisation has been a thing for a long time.

I know they've automatically boosted brightness in dark scenes for a long time too. It's not rare for people to upload a clip from a video game with a very dark scene and it's way brighter after upload than it was when they played or how it looks in the file they uploaded.

Re: What is HDR, anyway?

#200

Post by staticautomatic »

QuantumGood wrote: post #140
dahart wrote: post #123

It seems like a mistake to lump HDR capture, HDR formats and HDR display together, these are very different things. The claim that Ansel Adams used HDR is super likely to cause confusion, and isn’t particularly accurate. We’ve had HDR formats and HDR capture and edit workflows since long before HDR displays. The big benefit of HDR capture & formats is that your “negative” doesn’t clip super bright colors and doesn’t…

Adams adjusted heavily with dodging and burning, even working to invent a new chemical process to provide more control when developing. He was great at determining exposure for his process as well. A key skill was having a vision for what the image would be after adjusting. Adams talked a lot about this as a top priority of his process.

Contact printing on azo certainly helped!
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