What is HDR, anyway? • Hacker News Board

Re: What is HDR, anyway?

#131

Post by altairprime » Wed, May 14, 2025, 5:00 PM UTC

Suppafly wrote: post #95

dmos62 wrote: post #82

Earlier quoted context omitted.

That's not inherent to HDR though. BFV (unless I'm confusing it with something else) has a HDR adjustment routine where you push a slider until the HDR white and the SDR white are identical. Same could be done for desktop environments. In my experience, HDR support is very lacking in PCs atm. You can't even play Dolby Vision on Windows, which is the only widely-used HDR format with dynamic metadata.

>HDR support is very lacking in PCs atm. I think it's because no one wants it.

No; Windows 10 barely supports it, and of my hundreds of Steam games, exactly none have any code making use of it; seemingly only AAA mega-budget games have the pipeline bandwidth, but e.g. Dune Imperium and Spaceways have no reason to use it and so don’t bother. Windows 11 focused on improving wide color support which is much more critical, as any game shipping for Mac/Win already has dealt with that aspect of the pipeline and has drabified their game for the pre-Win11 ICC nightmares. Even games like Elite Dangerous, which would be a top candidate for both HDR and wide color, don’t handle this yet; their pipeline is years old and I don’t envy them the work of trying to update it, given how they’re overlaying the in-game UI in the midst of their pipeline.

(It doesn’t help that Windows only allows HDR to be defined in EDID and monitor INF files, and that PC monitors start shutting off calibration features when HDR is enabled because their chipsets can’t keep up — just as most modern Sony televisions can’t do both Dolby Vision and VRR because that requires too much processing power for their design budget.)

Re: What is HDR, anyway?

#132

Post by dahart » Wed, May 14, 2025, 5:01 PM UTC

4ad wrote: post #14

the__alchemist wrote: post #6

Earlier quoted context omitted.

Not in the more general sense! It can refer to what its acronym spells out directly: Bigger range between dimmest and brightest capabilities of a display, imaging technique etc.

No. HDR can encode high dynamic range because (typically) it uses floating point encoding. From a technical point of view, HDR is just a set of standards and formats for encoding absolute-luminance scene-referred images and video, along with a set of standards for reproduction.

I think most HDR formats do not typically use 32 bit floating point. The first HDR file format I can remember is Greg Ward’s RGBE format, which is also now more commonly known as .HDR and I think is pretty widely used.

https://www.graphics.cornell.edu/~bjw/rgbe.html

It uses a type of floating point, in a way, but it’s a shared 8 bit exponent across all 3 channels, and the channels are still 8 bits each, so the whole thing fits in 32 bits. Even the .txt file description says it’s not “floating point” per-se since that implies IEEE single precision floats.

Cameras and displays don’t typically use floats, and even CG people working in HDR and using, e.g., OpenEXR, might use half floats more often that float.

Some standards do exist, and it’s improving over time, but the ideas and execution of HDR in various ways preceded any standards, so I think it’s not helpful to define HDR as a set of standards. From my perspective working in CG, HDR began as a way to break away from 8 bits per channel RGB, and it included improving both color range and color resolution, and started the discussion of using physical metrics as opposed to relative [0..1] ranges.

Re: What is HDR, anyway?

#133

Post by Sohcahtoa82 » Wed, May 14, 2025, 5:03 PM UTC

nfriedly wrote: post #34

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…

A lot of monitors that advertise HDR support really shouldn't. Many of them can decode the signal but don't have the hardware to accurately reproduce it, so you just end up with a washed out muddy looking mess where you're better off disabling HDR entirely. As others here have said, OLED monitors are generally excellent at reproducing a HDR signal, especially in a darker space. But they're terrible for productivity w…

I think an OLED is basically an absolute necessity for HDR content.

My current monitor is an OLED and HDR in games looks absolutely amazing. My previous was an IPS that supported HDR, but turning it on caused the backlight to crank to the max, destroying black levels and basically defeating the entire purpose of HDR. Local dimming only goes so far.

Re: What is HDR, anyway?

#134

Post by mxfh » Wed, May 14, 2025, 5:03 PM UTC

sandofsky wrote: post #59

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…

> Does anyone else find the hubris in the first paragraph writing as off-putting as I do? > "we finally explain what HDR actually means" No. Because it's written for the many casual photographers we've spoken with who are confused and asked for an explainer. > 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 predictabl…

Maybe my response was part of the broader HDR symptom—that the acronym is overloaded with different meanings depending on where you're coming from.

On the HN frontpage, people are likely thinking of one of at least three things:

HDR as display tech (hardware)

HDR as wide gamut data format (content)

HDR as tone mapping (processing)

...

So when the first paragraph says we finally explain what HDR actually means, it set me off on the wrong foot—it comes across pretty strongly for a term that’s notoriously context-dependent. Especially in a blog post that reads like a general explainer rather than a direct Q&A response when not coming through your apps channels.

Then followed up by The first HDR is the "HDR mode" introduced to the iPhone camera in 2010. caused me to write the comment.

For people over 35 with even the faintest interest in photography, the first exposure to the HDR acronym probably didn’t arrive with the iPhone in 2010, but HDR IS equivalent to Photomatix style tone mapping starting in 2005 as even mentioned later. The ambiguity of the term is a given now. I think it's futile to insist or police one meaning other the other in non-scientific informal communication, just use more specific terminology.

So the correlation of what HDR means or what sentiment it evokes in people by age group and self-assesed photography skill might be something worthwhile to explore.

The post get's a lot better after that. That said, I really did enjoy the depth. The dive into the classic dodge and burn and the linked YouTube piece. One explainer at a time makes sense—and tone mapping is a good place to start. Even tone mapping is fine in moderation :)

Re: What is HDR, anyway?

#135

Post by miladyincontrol » Wed, May 14, 2025, 5:05 PM UTC

I do prefer the gain map approach myself. Do a sensible '32 bit' HDR edit, further tweak an SDR version, and export a file that has both.

Creative power is still in your hands versus some tone mapper's guesses at your intent.

Can people go overboard? Sure, but thats something they will do regardless of any hdr or lack thereof.

On an aside its still rough that just about every site that touches gain map (adaptive HDR as this blog calls them) HDR images will lose that metadata if they need to scale, recompress, or transform the images otherwise. Its led me to just make my own site, but also to handle what files a client gets a bit smarter . For instance if a browser doesnt support .jxl or .avif images, im sure it wont want an hdr jpeg either, thats easy to handle on a webserver.

Re: What is HDR, anyway?

#136

Post by miladyincontrol » Wed, May 14, 2025, 5:08 PM UTC

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…

Few things are in absolutes. Yes most consumers wont have every screen hdr nor 4k, but most consumers use a modern smartphone and just about every modern smartphone from the past half decade or more has hdr of some level.

I absolutely loathe consuming content on a mobile screen, but its the reality is the vast majority are using phone and tablets most the time.

Re: What is HDR, anyway?

#137

Post by kjkjadksj » Wed, May 14, 2025, 5:10 PM UTC

altairprime wrote: post #114

skhameneh wrote: post #29

Earlier quoted context omitted.

I’m under the impression this is caused by the use of “HDR mode”(s) and poor adaptive brightness implementations on devices. Displays such as the iPad Pro w/ OLED are phenomenal and don’t seem to implement an overactive adaptive brightness. HDR content has more depth without causing brightness distortion. In contrast, my TV will change brightness modes to display HDR content and disables some of the brightness adjust…

Apple’s method involves a good deal of what they call “EDR”, wherein the display gamma is ramped down in concert with ramping the brightness up, so that the brighter areas get brighter while the non-bright areas remain dark due to gamma math; that term is helpful for searching their WWDC developer videos for more details.

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 distracting.

Re: What is HDR, anyway?

#138

Post by zamadatix » Wed, May 14, 2025, 5:11 PM UTC

alerighi wrote: post #98

gwbas1c wrote: post #88

Earlier quoted context omitted.

> I don't own a single 4k or HDR display Don't feel like you have to. I bought a giant fancy TV with it, and even though it's impressive, it's kinda like ultra-hifi-audio. I don't miss it when I watch the same show on one of my older TVs. If you ever do get it, I suggest doing for a TV that you watch with your full attention, and watching TV / movies in the dark. It's not very useful on a TV that you might turn on wh…

I don't either see a point of having 4K TV vs 1080p TV. To me is just marketing, I have at my house both a 4K and a 1080p and from a normal viewing distance (that is 3/4 meters) you don't see differences. Also in my country (Italy) TV transmissions are 1080i at best, a lot are still 570i (PAL resolution). Streaming media can be 4K (if you have enough bandwidth to stream it at that resolution, which I don't have at my…

For TVs under ~80" I feel like you'd have to be sitting abnormally close to your TV for it to matter much. At the same time I think the cost difference between producing 1080p and 4k panels is so low it probably doesn't matter. Like you say, things like the backlight technology (or lack thereof) make a much bigger difference in perceived quality but that's also where the actual cost comes in.

Re: What is HDR, anyway?

#139

Post by zamadatix » Wed, May 14, 2025, 5:15 PM UTC

colechristensen wrote: post #73

dmitshur wrote: post #67

Earlier quoted context omitted.

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…

The cheap displays adding broken HDR400 support destroyed so much public opinion on HDR. Not actually providing a wider range but accepting the HDR signal would at least have been a minor improvement if the tone mapping weren't completely broken to the point most people just associate HDR with a washed out picture.

Re: What is HDR, anyway?

#140

Post by QuantumGood » Wed, May 14, 2025, 5:15 PM UTC

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.