High Dynamic Range Imaging

May 5, 2006 9:30 AM

High DynamicRange Imaging: The dawn of a new era? In computer graphics and cinematography, high dynamic range imaging (HDRI for short) is a set of techniques that allow a far greater dynamic range of exposures than normal digital imaging techniques. The intention is to accurately represent the wide range of intensity levels found in real scenes, ranging from direct sunlight to the deepest shadows. quote from HDR Wikipedia page
posted by spock (56 comments total)

HDR involves the use of two different techniques: Exposure blending and tone mapping. Photoshop tutorials: 1, 2, 3 and 4 and (for the Photoshop-challenged?) Photomatix: Tutorial part 1 and 2.
posted by spock at 9:31 AM on May 5, 2006

A stormchaser/photographer experiments with the technique including a night shot.
posted by spock at 9:35 AM on May 5, 2006

HDR: threat or menace? Since people discovered this little toy in Photoshop the net has been flooded with horrible unnatural images with giant halos and boring subject matter. For a taste of the frustration, see this Flickr discussion. Or any of the hideous images in Spock's second link. Or to pick on a good ol' Web boy, this photo. Or my own awful experiment.

Hopefully in a year or two the novelty will pass and we'll actually see something interesting come out of these tone mapping tricks.
posted by Nelson at 9:38 AM on May 5, 2006 [1 favorite]

I've yet to see HDR implemented in any game such that it wasn't immediately annoying.
posted by Ryvar at 9:44 AM on May 5, 2006

Valve Software has begun using HDR in all of their software releases, most notably in the Half-Life: Lost Coast tech demo and in the upcoming Half-Life2: Episode One release due out in June.

Other games have ridden on this technology bandwagon. This is a good thing.
posted by NationalKato at 9:44 AM on May 5, 2006

Ryvar, 'annoying?' Sure, Lost Coast may have been extreme in some of the beach scenes. Day of Defeat: Source was a bit annoying (except in how it forced snipers to not face the sun when looking through their scope), but the implementation in Oblivion (linked in my previous comment) worked perfectly, in my opinion.
posted by NationalKato at 9:46 AM on May 5, 2006

Any tool is only as good as the tool-wielder. Many of the less-than-appealing shots seem to be people who use Photomatix "dialed to 11". That isn't to say it might be a perfectly good tool if used with more restraint. I believe that Photoshop gurus will always have an edge over the automated tools, like Photomatix.

I think HDR has the potential to become the digital Zone System for color. (Speaking of which, why wouldn't it be great for black & white digital images? **I love b&w**).

Certainly HDR is bound to be controversial in some camps. That being said, photography left the bounds of pure realism some time ago and IMHO this has some interesting uses in the "art photography" arena.
posted by spock at 9:47 AM on May 5, 2006

Ug, my first thought was that these things look like they've been horribly photoshopped out of a bunch of different exposures -- and that seems to be essentially correct.

I've come across a couple okay HDR images so far, but it looks for the most part like people need to calm the hell down and figure out what they're doing.

It'll be nice when we have monitors with enough dynamic range themselves to display more...
posted by blacklite at 9:58 AM on May 5, 2006

I used the zone system with a 2-degree handheld spotmeter and Pan-X (ASA 25) years ago, and combining those negatives with good Agfa paper, was able to make myself and my photography teacher very happy.

Even using 35mm (a Leica with a Summicron 50mm), the range was --- well, nothing like what Ansel Adams did with his huge view camera negatives. But not bad for a teenager.

It made me see the world differently and that's never gone away, even as my eyes have gotten old and lost the ability to see contrast as well as they used to -- I know it's there, and the details are there in the darkest and lightest areas, so I work to see and record them.

If a digital camera ever becomes available that will capture the dynamic range of one of Ansel Adams's old black and white negatives -- we'll see the world a bit more like it is, as he did.
posted by hank at 9:59 AM on May 5, 2006

Yes, with the addition of several Photoshop filters, you too can be Thomas Kinkade!
posted by zabuni at 10:01 AM on May 5, 2006

The HDR in Oblivion is very nice, except that it makes the NPCs look even more like burn victims. It seems like it's something that's hard to get exactly right.

The flickr photosets are neat, but they just look like particularly keen photoshopping. They don't look "real". I think the point of the HDR effects in games is largely to more authentically simulate the experience of realistic light, so it seems like two different effects are at work here.
posted by selfnoise at 10:03 AM on May 5, 2006

Sadly, it's a bullshit buzzword that's applied to many largely unrelated things most of which are no different to what we were doing before.

(the only meaningful usage is in relation to 3D graphics rendering)
posted by cillit bang at 10:06 AM on May 5, 2006

I've yet to see HDR implemented in any game such that it wasn't immediately annoying.

I liked how Shadow of the Colossus used "fake" HDR effects, if you're inside a building the outside is shown as a white glow, and if you're outside the insides of buildings are darkened. Black uses what I think are fake HDR effects too, in some parts of the game the ends of tunnels will glow even though there isn't anything that bright at the end, it just being placed for dramatic effect.

Actually, I think "faking" HDR in videogames can result in visuals that are more pleasing than actual HDR, I think the problem is that it's more labour intensive.
posted by bobo123 at 10:06 AM on May 5, 2006

selfnoise, I agree. For me, the biggest benefit to all this HDR hoodoo in gaming is that they're including an auto-adjust feature in the exposure, so that the exposure on-screen seems more like the human eye when changing from a bright area to a darker one. I also like how the surface textures adjust to the light sources.
posted by NationalKato at 10:08 AM on May 5, 2006

I think it's pretty cool.
posted by Espoo2 at 10:10 AM on May 5, 2006

If a digital camera ever becomes available that will capture the dynamic range of one of Ansel Adams's old black and white negatives -- we'll see the world a bit more like it is, as he did.

That's precisely what HDRI allows digital visual artists to do. In other words, HDRI is just an implementation of the zone for digital imaging.

Sure, a lot of these images just look photoshopped, and they are, in fact, photoshopped. But HDRI uses photoshop like a very precise enlarger, not as a graphics tool.

the exposure on-screen seems more like the human eye

That's HDRI in one phrase.
posted by sequential at 10:13 AM on May 5, 2006

bobo- Battlefield 2 has some "fake" ish HDR features that are fairly subtle and very nice (with lighting set on "High"). So I think you are right in saying you can do it either way. And Bloom is just as easy to abuse as HDR, sadly: there are too many games out these days that use Bloom effects "just because" (see D&D: Stormreach).
posted by selfnoise at 10:14 AM on May 5, 2006

cillit bang writes "Sadly, it's a bullshit buzzword that's applied to many largely unrelated things most of which are no different to what we were doing before."

That's the impression that I'm quickly getting; it seems to mean very different things when applied to digital photography and CG rendering.

This is all new to me, and I have a fundamental technological question. Where is the dynamic range bottleneck in digital imaging? The CCD/CMOS chip? Display devices? Printers? I know that there are CCD chips (used in astronomy and microscopy) out there that can capture far more dynamic range than the human eye can see; is dynamic range simply not a priority in digital cameras?
posted by mr_roboto at 10:16 AM on May 5, 2006

All the pictures look over-worked and unnatural. HDR is truly amazing for dynamic ranges one can capture - but unless you have an output device to match, you gain nothing. Unless you have an HDR capable monitor (are there any?) these pictures look like nothing more than someone gunning the saturation slider to full.
posted by Qubit at 10:24 AM on May 5, 2006

On the whole, I don't understand the negative reactions - sure, a lot of the images that are being produced look "unnatural", but, to me, that's not necessarily a bad thing - I think a lot of the results are artistically very interesting, striking even.
posted by kcds at 10:26 AM on May 5, 2006

Photography 2.0?
posted by knave at 10:34 AM on May 5, 2006

I think the HDR effects in the Counter-Strike Militia map were done just right-- subtle, but enough to give the lighting a bit more life. As you step out of the shadows the bright saturated highlights fade-in mimicking your eyes adjustment.
posted by justkevin at 10:41 AM on May 5, 2006

I think it looks good on some night shots or low-light shots like this one. Only a little halo effect, but it's pretty crisp with lots of detail and you can see the stars in the background.
posted by p3t3 at 10:43 AM on May 5, 2006

Yes, HDR means different things to different people. I'm surprised to even see the video game discussion here next to the photos. I guess the common thread is both HDR in games and HDR in photos are doing the same thing: working with image data with more dynamic range (ie, more contrast) than can be displayed on today's 24 bit displays. Then you use some funky tone mapping algorithm to bring your HDR image back down to your computer screen or JPG.

Doing image processing with higher precision is a good thing. It's why going from RAW to 16 bit images in Photoshop is better even if you're producing an 8 bit JPG output. And it's why music studios use more than 16 bit samples in the mastering process. The problem is that Photoshop and Photomatix both now have a easy-to-abuse automatic tone mapping algorithm that results in freakish images. See how the tree is glowing in that photo? Yuck.

The "fake" HDR used in many video games is often just a little Bloom applied as a shader on top of bright images. It's not a bad approximation of the bleed from a bright light source. Tron 2.0 was the place I saw it first.
posted by Nelson at 10:45 AM on May 5, 2006

Where is the dynamic range bottleneck in digital imaging?

Fundamentally, it's in the display. The real world contains a much greater range of light values than a monitor could possibly display. An object indirectly lit by the sun on a bright sunny day is producing more light than your monitor is capable of generating.
posted by justkevin at 10:47 AM on May 5, 2006

p3t3, the problem with that photo is that really all they've done is used Photoshop to edit in the stars. Touting this as a "benefit of HDR" is just crap.
posted by cillit bang at 10:49 AM on May 5, 2006

seriously you guys, any tool can be abused. i've been very happy with the results of photomatix. yes, their defaults are horrible. yes you have to tweak a bit. but how is that any different than the normal ACR flow? you have to tweak and tweak and tweak...

you don't "gain nothing". this isnt the best sample image, but look at the details behind the car in the garden. they are pretty much missing from the ACR processed image, but look great in the photomatix version.



more examples if i get motivated...
posted by joeblough at 10:56 AM on May 5, 2006

the implementation in Oblivion (linked in my previous comment) worked perfectly, in my opinion.

I agree with selfnoise, the sun looks nice but people look dreadful. I turned it off. Bloom doesn't make the world look like a 15 year old brighness/contrast job.
posted by 6am at 10:59 AM on May 5, 2006

HDR right now is going through alot of the same things that Bryce3d and Poser went through, a whole lot of cheese and not much meat. Although its been common knowledge in the CG and compositing world with image based lighting and such, with CS2 and Photomatrix a lot of people are playing around with it. Check out the True Tone High Dynamic Range group for some HDR photos that don't have that surreal amateur look.
posted by phirleh at 11:03 AM on May 5, 2006

I thought Valve did a nice job with HDR in their Half-Life 2: Lost Coast demo. It was generally very subtle unless I was deliberately looking for it, and for the most part, I only really noticed it (and missed it) when I turned it off again. And that's the nice thing: you can turn it off if you don't like it or it's slowing your machine down (self-link).

In games, it's the kind of thing I'd enable in single-player, if it didn't destroy my computer's performance. Multi-player (like Day of Defeat: Source), no way. I stink enough without giving myself more of a disadvantage.
posted by notmydesk at 11:12 AM on May 5, 2006

As others have said, this is nothing new, as far as the flickr implementation goes. In most cases it is the glorified cuttin gand pasting of multiple exposures.

This only has meaning if you have a HDR monitor, or if you are printing the images in a way that can take advantage of all of that extra information.

This was all covered very well last October: Previously on Metafilter
posted by hartsell at 11:12 AM on May 5, 2006

zabuni has it right. My other thought on looking at most of these is that they have the surreal look and glow one sees with infrared photography. But there are a few images I really like out there and this has a lot of potential, especially when display and print technology progresses.
posted by TedW at 11:23 AM on May 5, 2006

As I understand it, even good DSLRs only have about a 6 stop range possible in their CCD. If the scene you are shooting is low contrast (or you are going for the sillouette against the brighter background look) that's fine. But the majority of scenes have a much wider brightness latitude.

Example: A scene with a 10 stop exposure range:
-5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5
Expose for the "middle" and you get:
-3 -2 -1 0 +1 +2 +3
The parts of the scene brighter than +3 are blown-out (no detail) and the parts of the scene darker than -3 are black (no detail). Detail is there, if expose for it, but your choices are:
-5 -4 -3 -2 -1 0 +1 (even more high-end blown out)
or
-1 0 +1 +2 +3 +4 +5 (even more shadows going black)

As I understand it, HDR is taking three exposures (or more) and combining them. A lot of DSLRs have a setting for doing the exposure bracketing automatically (click-click-click) Clearly this won't work well for moving objects or handheld shots.

We're also talking about using RAW here, because if you're shooting JPEG the camera has already thrown away a lot of bytes of info to make the JPEG.
posted by spock at 11:25 AM on May 5, 2006

By the way, the halo or "glow" that several people are referring to seems to be something you get with Photomatix. I don't see that in the images by people who "roll their own" HDR using Photoshop. I think everybody agrees that the halo makes it look artificial.
posted by spock at 11:40 AM on May 5, 2006

I've experimented a bit with HDR as I understood it, and the results weren't particularly garish or unrealistic. It did provide detail in areas that would otherwise have been blown out or deep in shadow. But the Filckr pictures in the first link definitely demonstrate how it can be abused.

I've always though that one of the ways that both film and digitial fail to capture what I see is due to the lack of exposure lattitude. Our eyes adjust alot better to differences in light than film does, particularly in backlit situations and other situations with extreme differences. HDR, and direct support for it in digital cameras, would just give more options for manipulating exposure AFTER the photo was taken.

I don't think realism is an issue, since the whole act of taking a photograph involves so much interpretation, through lenses, film, ccds, long before a file hits photoshop. I guess realism, in that context, is about matching your perception of the scene, and I think that HDR can help with that.
posted by beegull at 11:45 AM on May 5, 2006

I have to say, I actually like the effect in most of those flickr photos. I agree that's it's "unnatural" but that's exactly what I like about it - it's like the world transformed into the cover of a metal album. Magic-looking and alien. Sure, it gets old very quickly when applied to landscape after landscape, but I imagine there could be a lot of good uses for it.
posted by Drexen at 11:48 AM on May 5, 2006

It's not just the halo - although I don't have a big problem with these images, I refuse to believe this is anything CLOSE to the "dawn of a new era" or new paradigm or new technique etc.

It's most visible in motion in 3D rendering and that's probably where it should stay for the most part.
posted by BlackLeotardFront at 11:50 AM on May 5, 2006

The problem is that people just throw some bracketed photos into a processor and don't really know what they're doing. I spent five hours getting this to look natural, but it was manual masking to get the job done. Most of the photos (esp that flickr link) just look rendered.
posted by notsnot at 12:11 PM on May 5, 2006

I spent five hours getting this to look natural

I would prefer a sensor in the camera which could capture a dynamic range equivalent to film. (by the way I don't think that image, beautiful as it is, looks natural.)
posted by caddis at 12:32 PM on May 5, 2006

HDR is a great idea. I want 11 stops of contrast, not 6 or 7, as is the norm for color slide film and digital sensors.

HDR is a tool, for me, with which you can try to get those 11 stops. But using it to get a realistic 11 stop range of tones in a photograph is really frickin' hard. I've not yet been able to get one that I like.

But if I can figure it out, I'll be happy, as ND-grad filters are a royal pain in the ass to use (and good ones really cost a pretty penny). And I'd love to really use the Zone system in digital color.

As HDR stands right now (as represented by the Flickr HDR pool), it's a toy for people to make surreal, super-saturated pictures. That's all fine and dandy. I don't like it, and that's not what I want to do with it, but it's art and people can do whatever they like. I'm hoping for photo-realism; others like and want photo-surrealism.

I had no idea there was HDR for video games.
posted by teece at 12:33 PM on May 5, 2006

Low rent hdr!
Make yer own unsharp mask:

1.Create a duplicate layer;
2.Blur the duplicate layer with the Gaussian Blur filter (around 3.5 pixel radius):
3.desaturate the duplicate layer (shift+cmnd+u);
4.invert the duplicate layer(cmnd+i);
5.Change the duplicate layer's blend mode to Overlay;
6. Fiddle with the duplicate layer's opacity (try aound 30%).

This mimics an old-school darkroom technique I learned back in the day for pulling out detail when printing blurry and/or underexposed large-format negatives by literally sandwiching them with duplicate positives, slightly blurred.

An lo-res example:

I use it often enough to keep it in my actions palette and assign it a keyboard shortcut.
posted by squalor at 12:36 PM on May 5, 2006 [3 favorites]

32 bit sensors are definitely where it's at, but they're a long way away in any usable, commercially available camera. HDR displays have at least been demonstrated, and I believe 1 or 2 are actually available.

As far as the super-craptastic halo effect demonstrated on Flickr, it can be avoided. It is the default rendering from Photomatix (I believe and I've only used the free version). In Photoshop you can get this effect when down converting but you have to work at it.

Besides the 3D and film/video people, the only professionals I encountered using it are people who shoot architectural interiors. It's very useful in that field because it allows you to shoot in the natural light of the space (as opposed to setting up natural looking artificial light).

I've used it in several landscapes, it's great as long as there's no wind. If nothing else, it forces you to bracket, so even if you don't end creating the HDR, you definitely get the shot.
posted by doctor_negative at 12:49 PM on May 5, 2006

Qubit: Unless you have an HDR capable monitor (are there any?)

Sort of. Check out Sunnybrook and Brightside displays, which I gather are related in some way. Far too expensive for mere mortals to use for anything fun just now. But there's nothing terribly exotic about the basic technology, so if the demand develops, they will probably be available eventually.
posted by Western Infidels at 1:32 PM on May 5, 2006

I've seen the Brightside displays in person. They're insane. You can't look at normal monitors the same way after.

(Brightside basically puts a grid of 1watt LEDs behind the screen. When it's black, they're off. When it's full white, it's a watt of light screaming at you. Infinite contrast ratio!)
posted by effugas at 1:42 PM on May 5, 2006

I'm not sure if the shots that Max Lyons technically count as HDR, but his images seem to have a very broad dynamic range, and they're gorgeous -- not at all fake-looking. There's a separate section for what sounds like HDR photos (under "blended exposures") but it sure looks like all of the photos on the site are essentially the result of the same technique.
posted by odin53 at 1:49 PM on May 5, 2006

squalor: Make yer own unsharp mask...

That's great, but is it any different from the unsharp mask tool that is built-in to most image-editing programs? I know the GIMP, for one, does USM in a multi-step, multi-layer process that I had assumed was similar to what you propose. Some people propose that local contrast enhancement be done with the USM tools.
posted by Western Infidels at 1:55 PM on May 5, 2006

Great technique squalor; I'll remember that one!
posted by odinsdream at 2:50 PM on May 5, 2006

Reminds me of the old post cards and travel ads from the 50's. It's an impossibly colorful world that I want to live in. If only my feeble rods and cones could reproduce it in real life.
posted by Blingo at 3:15 PM on May 5, 2006

That's awesome, squalor, flagged as fantastic. Best of all for me it doesn't require multi-exposure/works with a handheld shot.
posted by juv3nal at 3:52 PM on May 5, 2006

I agree with kcds. This may not look 'real', but it is unique. The images in the movie Spun did not look 'real', but they were unusual. I am experimenting with ways to acheive this in video. If possible, it would certainly be a unique way to eliminate that annoying video look.
posted by Occams Hammer at 4:03 PM on May 5, 2006

I agree with kcds. This may not look 'real', but it is unique. The images in the movie Spun did not look 'real', but they were unusual. I am experimenting with ways to acheive this in video. If possible, it would certainly be a unique way to eliminate that annoying video look.
posted by Occams Hammer at 8:00 PM on May 5, 2006

Methinks you'd have to film it with a light splitter that would record three negatives simultaneously, one being under-exposed, one just right, and one over-exposed.

Then, you'd have to combine these in post.
posted by odinsdream at 8:36 PM on May 5, 2006

A fun variation on the HDR theme: HDTR

HDTR = High Dynamic Time Range. It's a method for showing the passage of time within a single image. A cool concept from someone with a unique ability to visualize complex data in new ways (IMHO).
posted by exon at 8:42 PM on May 5, 2006

I enjoy having shadows in my pictures and you'll have to pry them from my cold, dead hands.
posted by Poagao at 2:30 AM on May 6, 2006

Make yer own unsharp mask...
Actually a classic darkroom technique that is unrelated to increasing dynamic range.
posted by TedW at 7:52 PM on May 6, 2006

This is fantastic!

We are working on a machine vision application at work, and one of the things we're having problems with is getting enough contrast out of images of brightly lit, shiny metal tubes. So after reading this, I did a quick googling for "HDR machine vision camera" and got this (discontinued) model. Judging by the results in the user manual[pdf], we could drastically improve our performance using this technique.

Thank you Metafilter!
posted by Popular Ethics at 7:55 PM on May 7, 2006