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High Dynamic Range (HDR) Technology Analysis
THG writes "CoolTechZone.com has published an analysis of Valve's High Dynamic Range, or HDR, technology that enhances graphics in video games. This new video/gaming graphics technology is expected to debut soon with Valve's Half-Life 2: Lost Coast title. According to the article, 'HDR, or High Dynamic Range, is a lighting process that's been designed to emulate in-game or artificially generated lighting to closely mirror the changes we see in the real world. In simpler terms, HDR allows you to make the objects brighter by allowing them to use the full brightness capabilities of the monitor and not just the brightness level at which they have been shot with (or rendered with) in the scene.'"
HDR (High Dynamic Range) Technology: An Overview
Written by Varun Dubey
Manufacturer: Various
Monday, 31 October 2005
(Review) - We've all played Half-Life and it's sequel Half-Life 2. The difference between the two games, in terms of graphics, is tremendous, and now Valve has gone ahead and updated the gaming engine to give you a level of detail and realism that you thought wouldn't be possible until perhaps the next round of game releases.
HDR, or High Dynamic Range, is a lighting process that's been designed to emulate in-game or artificially generated lighting to closely mirror the changes we see in the real world.
In simpler terms, HDR allows you to make the objects brighter by allowing them to use the full brightness capabilities of the monitor and not just the brightness level at which they have been shot with (or rendered with) in the scene.
HDR is, by definition, the ratio of the largest to lowest measurable value of a signal. As of today, the 16-bit formats use color component values from 0 (for black) to 1 (for white), but you can't define colors with increased vibrancy and shine by inputting value 2 for white to make it whiter than its traditional shade. Think about your breathing. That's right - inhale and exhale voluntarily. This can limit lighting effects such as the glint on the metal blade of POP Warrior Within.
Using HDR, you can specify values that are far outside the redundant 0-1 ranges we are used to currently. To give you an everyday example, when you drive on a sunny day, it often happens that the minute you come out of the tunnel, the sunlight seems blazingly brilliant as your eyes take sometime to adjust to the difference in the light intensities. In a game like NFS, replicating this realistic phenomenon is difficult and nearly impossible for the lack of the ability to specify whiteness beyond level 1, but with HDR, you can accomplish just that, which is why it's important to gamers that demand realism from their games.
Up until now, such effects were being achieved by a technique known as Blooming. This technique allows you to let the light from an overly bright object spill on to the particles around it, thereby making them appear brighter and ensuring enhanced visibility in titles.
The process, however, does not just work to increase the brightness of whites, but it also ensures that the blacks appear blacker and deeper while enhancing the subtle details of the image.
How does it work? Traditionally, images are stored in the RGB format, where each pixel knows exactly how much of these three colors it's supposed to display to give you accurate images.
The problem with this is that an image might be very bright, but how much of that brightness we see is dependent solely on the monitor we are displaying it on and no monitor in the world today can display anywhere close to the range of brightness levels that we can experience through our eyes.
We all know that we can shoot various photographs of the same scene and make it look completely different by just changing the exposure settings. For instance, if you're taking the photographs of the night sky in the Auto mode of your camera, it will come out mostly black and will be pretty much useless, but if you put the shutter speed at around 10-15 seconds and then take a photograph by keeping all other settings constant, you will get a completely different look and feel of the same night sky with greater depth and detail that you missed earlier with Auto mode. The problems with this kind of photography are obvious because if your scene has a bright object in it, it will get completely killed due to over-exposure.
Basically, if you take picture with exposure at a low setting, you'll be able to capture greater details of overly bright objects, and if you take the exposure settings to a very high level, then you'll be able to get the images of even the most dimly lit objects and here in lies the contradiction.
Personally, I liked AnandTech's review from a month ago better. If you're interested, its available here.
"This new video/gaming graphics technology is expected to debut soon with Valve's Half-Life 2: Lost Coast title."
Its okay to post old news, but Lost Coast is already out, as is DoD:S which also uses HDR.
Pain lasts, kid. Its how you know you're alive. Sometimes I think this growing up thing is just pain management-TheMaxx
http://debevec.org/ lots of info here
My wish list for Christmas 2005:
- Ending world hunger
- Finding a cure for AIDS
- Making objects brighter by allowing them to use the full brightness capabilities of the monitor
Only two more to go! Thanks, Slashdot, for bringing this to my attention!
For one thing, Lost Coast is already out, and has been since last week.
For another, the first Valve game to use HDR is DOD:Source, and that's been out quite a while already.
And finally, Valve didn't actually invent HDR, so other stuff has already used it.
I think that striving for accuracy and balance of the elements is probably more important than striving for the maximum ____ your system can deliver.
Brightness values should have NEVER been bounded above in the first place (and now that I think of it, bounded below, either). The video card should be charged with computing everthing and only then "flattening" the image into something the monitor can display. It could even add some bloom automatically. HDR and motion blur will do wonders for realism...
Quid festinatio swallonis est aetherfuga inonusti?
Africus aut Europaeus?
why, why did i get a laptop for gaming? my computer can barely render the Sims 2 - yet guild wars runs fantastically... im not getting my hopes up about running Civilization 4... and its only a year and a half old. the sad part is, my card is better than half the laptops cards out there (which have shared memory and wide-screens!).
i remember years ago, i could still play the games fine if i just turned the graphics down - but that doesnt work anymore! my GeForce 2 lasted more than 2 years, but this one barely lasted over a year!
one things for sure, i think these games need to allow more user control so I can set it at a reasonably low level, and support for widescreen. we need more flexible graphics engines before we add more insane quality/lighting effects!
After playing Half Life 2: Lost Coast with Full HDR at 1280x1024 and settings all the way at max, I came away with the impression that HDR is really quite nice. Comparing screens with normal filters and HDR, HDR is much more realistic. When you look at water reflections HDR is invaluable. Sun reflections especially looked impressive. Where normal filters made the bright spots look gray, HDR made everything shine and bleed a bit. It was quite accurate as far as the water went. Now, what I didn't think was realistic, was HDR used in the distance. There was that seem bleeding effect across open windows and such. Also, the effect is sampled every so often, I don't know what the sampling rate was there, but a couple times i noticed a slow sampling rate that wasnt entirely realistic. Towards the end of the Lost Coast level, I was impressed by the light coming in from the windows (you'll know what im talking about if you've played it). They were stained glass windows and first there was a dull light in them, but when you shot them out, a big blast of white/yellow light shines through that looks quite good. My conclusion is that HDR is good, but they should up the sampling rate in HL2LC and also change how its viewed in the distance. But what do i know... anyway, thats how i saw it.
The truth is, our computer monitors are very limited in the range of colors they can reproduce. We have been stuck with 8 bit RGB for a long time now, I'm surprised we haven't moved on to 16 bit per color or even floating point by now. Internally, video cards in the future will render using floating point arithmatic, but I'm guessing they will still be transmitted as 8 bit per color RGB. Not only that, most image file formats like JPEG are only 24 bit.
Furthermore, we really need to increase contrast ratios of monitors. Having a single back-lit isn't really good enough. I would imagine something containing say a few thousand high intensity white LED's in an array would be good. This way, you could only light up sections of the monitor that need high dynamic range. With enough LED's (a few thousand, not one for each pixel) you could produce quite an interesting effect. I believe there is a monitor that some company is working on that does this.
Of course, I probably should'nt be complaining at all. I'm very happy with my 24" HD monitor I just installed today...
The provided definition of HDR isn't very accurate. From Game Developer magazine's August 2005 issue:
"High Dynamic Range (HDR) rendering is a technique used to retain color precision of a rendered scene as it goes through the rendering pipeline...
For applications, especially games, this means that our scenes will be rendered in a more realistic manner in terms of lighting. Using high dynamic range rendering we can add a great deal of detail to our applications by retaining as much light information as possible. This will then cause our objects and surfaces to be displayed in a way that comes closer to resembling real life than ever before.
The problem with non-HDR games is that traditionally, the color precision of a rendered scene is lost, and the rendered display is limite to a low dynamic range of color values between 0 and 255. In the past, this limitation was mainly a result of PC or console hardware only supporting integer buffers, which has a limited range of precision when compared to floating point buffers. Thus, to perform HDR rendering we will need to render our scene to an off-screen floating-point surface, so that the data can be manipulated and made ready to be displayed on the screen."
Also, it's not Valve's technology. They've implemented it in the Source engine now, but they didn't invent it and I'm pretty sure they're not the first to use it.
The problem I see with this is phosphor burnout..... running very high brightness areas on screen is going to seriously reduce the lifespan of crts. With everyone going to flatpanels, this might not be so bad, but it's still not good news for crts...... I have some seven year old displays that have faded rather drastically over their lifetime. With this technology they sure as heck would have gone black long ago....
I've no idea how current flatpanel LCD displays will age. Looking at my laptop displays, they might hold up pretty well....
I got tired of the brightness being a hair low on my viewsonic 19", So I used the color balance settings in the nvidia driver to push the low end up enough to see. My display has faded MUCH more rapidly since I did that.
Since this is a technology included in software, why is it listed as hardware?
Having been previously and currently employed in labratories and RND departments, considering myself to know something about the subject ... id like to point out that this is a TECHNIQUE, not a Technology.
Religion is a gateway psychosis. -- Dave Foley
HDR in computer graphics is typically a big deal as much research goes into mapping large range algorithms into graphics hardware that typically operates in the 0..255 range for each component. As hardware becomes more and more capable, floating point blending ops on 16-bit floats (which are capable of "high dynamic range"), an entire class of algorithms becomes unnecessary.
_ posure.htm
Enter the exposure function. Given an image of undefined range, map it into what is displayable. This is somewhat similar to how pictures of various brightness come out on film.
Here is a brief, almost layman description of what an exposure function does (I consider this a great intro on the subject).
http://freespace.virgin.net/hugo.elias/graphics/x
I think, if you want to be precise, what Valve did in Lost Coast should be called Paul Debevec's High Dynamic Range.
High Dynamic Range lighting is a technique. Valve's implementation of that technique in the Source engine is a technology.
High Dynamic Range is also a useful tool in photography, especially for digital photographers who find that the useful dynamic range of a digital camera is less than that of an equivalent film camera. Multiple-exposure bracketing can be combined with the use of special processing software in order to yield images that would be difficult to obtain with a digital camera, or sometimes even a film camera.
... designed to emulate ... lighting to closely mirror the changes we see in the real world."
Photoshop CS2 includes this technology out of the box (Photoshop CS2 HDR) -- in the demo page, notice that the sky is properly exposed as well as the vegetation on the hill in the foreground; this would be impossible to capture with many cameras. As the article linked by the original post states,
"HDR, or High Dynamic Range, is
And indeed that's what the photographic equivalent does. Unlike a camera, our eyes can properly "expose" the ground as well as they can the sky in the same scene. In fact, this is mentioned on pages 2 and 3 of the linked article in the original post.
More:
HDR - High Dynamic Range Compression - a Photoshop plugin
The Future of Digital Imaging - High Dynamic Range Photography (HDR)
Aizu University's Atrium High Dynamic Range Source Images
High dynamic range imaging - Wikipedia, the free encyclopedia
Stitched HDRI
If you would like to try this yourself, many digital cameras have a bracketing feature. I'd suggest at least five exposures, separated by one half stop or one full stop. However, it does not work well for moving objects since there will be a short amount of time that elapses between exposures.
Here is my first attempt:
High Dynamic Range Candy Corn
This particular shot was taken with a Canon EOS 1Ds MkII camera and manual bracketing, although I've made other successfull attempts with the bracketing feature of my Nikon D70.
i am a soviet space shuttle
Lost Coast is already out. And yes, HDR looks great - it was probably the most impressive part of Lost Coast. I hope that we see it in all future 3d games.
Not even close.
It's called "turning up the contrast".
What's really going on is that most games in the past have been tuned for the rather limited dynamic range of CRT's. A CRT can't do much more than a 30-1 range without saturating the phosphors.
But the newer and better LCD displays can do around TEN times better. So it's time to turn up the contrast.
Nothing much more high-tech than that.
+1 for AnandTech and decent journalism.
Looks like they apply auto-levels to each frame. That shouldn't affect performance a lot, btw. It is really a work-around for bad rendering. They could fix low dynamic range earlier in the output pipeline.
A chain is only as strong as it's weakest link.
Too bad the BrightSide display is "a little costly"... (Think several small cars -costly.)
.: Max Romantschuk
Not another one of these. Theres been a hundred if theres been one. I probably know as much or more about modern 3d engines than the guys who write these articles anyway. Unless I see it at beyond3d, it probably not worth it.
Half Life 2: Lost Cause!
I mean seriously, I would rather have had them work on their anti-hacking technology rather than this.
One of my friends has a Geforce 7800 GTX. Here are some screenshots of Farcry with HDR enabled.
The major part of HDR (excluding glare and all that), is that it is a way to model the way that the iris (the black bit in the middle of your eye) opens and closes at different brightness levels.
There is something missing though, which I think would be beneficial. Basically, the eye has rods and cones for luminance and colour respectively. The rods are far more sensitive than the cones, with the result being that in very low light conditions, we see in greyscale. I have never seen this effect in a game (or film), and I think it would really enhance the realism, especially in darker games like Doom3. It would be even better if the display could become slightly blurry and noisy as the rods are not as high resolution as the cones.
In a game like NFS, replicating this realistic phenomenon is difficult and nearly impossible for the lack of the ability to specify whiteness beyond level 1, but with HDR, you can accomplish just that, which is why it's important to gamers that demand realism from their games.
So you're saying that this one goes to eleven?
HDRI has been around for a long time --since the late '90's. I don't understand why this is considered new, especially since Paul Debevec introduced this at Siggraph in '99 (?) in Fiat Lux. It's been in almost all the latest big VFX movies to date. HDRI is not a "a lighting process that's been designed to emulate in-game or artificially generated lighting". It is a method of lighting scenes using real-world lighting scenarios. I suppose this is new to the video game industry, but this has been around for quite awhile, so the article is a bit misleading. For more info about HDRI, go to Paul Debevec's site: http://debevec.org/
HDR has been around for a longer while than you think. It has been used in games before, it has been demoed before. Some of you may recognize HDR in the form of light blooms, especially from the earlier screenshots of the Unreal 3 Engine, as seen here:
HDR Glow in Unreal 3
Although some say light blooms are NOT high-dynamic range (which is true for the case where you just make something radiate light in a way that washes out details of objects around it - see here), light blooms can be done with high-dynamic range color, which is what the Unreal 3 Engine page mentions in a brief caption for the above picture.
Anyways, there are other games that ALREADY do HDR, such as Far Cry (with patch 1.3 or above). The best place to get a good view of it is ON a beach in Far Cry that is directly in the sun. It is funny that Far Cry has been ignored as the first of its kind in many things, but it really did do a lot of stuff that Doom 3, Half Life 2, etc. did, except earlier. It was also virutally bugless, compared to for example, the stuttering bug common in Half Life 2. Most are misinformed in crediting games such as HL2 or D3 in bringing in the generation of shader-heavy games (aka 'next gen' games).
That being said, if you don't know what HDR is, the Anandtech Article on HL2:TLC is a good read.
Graduated neutral density filter. Cokin makes a nice kit.
Actually a whole lot of what gets done in photoshop can be done much faster at exposure time. Like lighting colour adjustments (warming/cooling filters), Increasing colour saturation (polarizers), selective focus (large aperature and/or vaseline smeared UV filter), perspective correction (proper camera placement and/or tilt/shift lens or a View Camera), etc.
Any screenshots or video demo anywhere?
The Doom 3 engine supported HDR, while the game didn't make use of it. They did that for self-shadowing, too.
I'm a little curious to know why no one on this thread has mentioned the guy who first started implementing it the way it is used now in the first place. We might as well just forward a link to his site and Siggraph papers.
Paul Debevec's homepage
Sure, and those filters are indeed very useful. My comments are meant to be interpreted as applicable to a camera with a lens attached and no filters. But you are right - GND filters are fantastic for landscape shots.
i am a soviet space shuttle
There was good article on Ars Technica as well, going into a fair amount of technical detail into why Valve's HDR implementation is interesting, and why it took so long (and so many attempts) to create.
;-)
I'm still waiting for the updated Source SDK so I can build maps using HDR - it's something I'm really looking forwards to. Eat your heart out, darkness-obsessed Doom 3 and friends!
Tedious Bloggy Stuff - hooray?
I think some other poster did, run a search on his name... I didn't because I hadn't heard of him, but I'll look at that when it isn't 3AM.
Sidenote: Your username makes me wonder if you're a VW driver. Are you?
i am a soviet space shuttle
Finally! I've been waiting for the day developers would decide my graphics card with its high-res 32-bit textures displayed on 1600 by 1200 with maximum draw distance, 3 kinds of filtering, and 8 layers of model mesh effects would look better washed out anytime the sun is up.
I can see it now- Unreal Tournament 2007: Pre-Order and get a FREE pair of Eagle-Eye sunglasses using patented NASA anti-glare technology!
Just give me the damn Kryptonite fog already. Serves us right for letting game designers use that much texture memory for crap like sand anyway. What did we think we were supporting?
Anyone wanna play Duke Nukem 3D? Now THAT game had some good graphics.
Or some MultiTheftAuto VC before the HDR-compatible windshield glare updates?
Take a picture of white sheet of paper and a flashlight turned on. Decrease brightness by ten. With regular picture (brightness 0-255) paper will look as dim as flashlight. With HDRI (0-gazillion) actual brightness of flashlight will be preserved and look much brighter than white sheet of paper.
BTW: Quake1 had poor mans HDR - palette with few colors which weren't affected by lightmaps.
That is the worst explenation of HDR I have ever seen. Clearly missed the point.
sudo ergo sum
FiringSquad did a review on it a few months ago.
Ant(Dude) @ Quality Foraged Links (AQFL.net) & The Ant Farm (antfarm.ma.cx / antfarm.home.dhs.org).
Day of Defeat: Source
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/kaffein
Simulation of the pupil wide open from exiting a dark area:
http://images.filecloud.com/57502/dod_anzio0005.j
A little less open:
http://images.filecloud.com/57503/dod_anzio0006.j
Eyes getting pretty adjusted here:
http://images.filecloud.com/57504/dod_anzio0007.j
Eyes back to normal:
http://images.filecloud.com/57505/dod_anzio0008.j
Btw Far Cry 1.3 had HDR.
HDR is old hat now, seriously. It was fun to see in a few games and I liked the tech demos back in 2002 on my Radeon 9700 Pro but I honestly don't care about it anymore, what is the big deal?
"HDR allows you to make the objects brighter by allowing them to use the full brightness capabilities of the monitor."
Pretty bad lie. By using a #ffffff color you already "use the full brightness capabilities of the monitor", unless you count turning up the brightness setting in yout monitor. As it has already been said, it lets the objects be brighter in the internal calculations, not on the monitor.
Either HDR is a bunch of crap or the explanation is. I'm reminded of Nigel of Spinal Tap explaining how his amp is better because it goes to eleven.
I hate to be "one of those people" but this article sucks - four really short pages and not a single screenshot - WTF?!? If you want to *see* Valve's HDR, you'll do no better than bit-tech's series of articles:
Half Life 2: Lost Coast HDR overview
Half-Life 2: Lost Coast review
Half-Life 2: Lost Coast Benchmarks
Day of Defeat: Source review
HDR, Half Life 2: Lost Coast, and the Future of Gaming -- Has a lot of good examples of what HDR exactly involves.
They wrote about Valve's HDR implementation WITHOUT any screen shots included? Slashdot, can I have the 20 minutes of wasted time back please? Thx
Another article about HDR that doesnt actually explain what is really is. It starts off ok but then falls appart. Bloom isnt HRD, Exposure control isnt HDR, Radiosity isnt HDR...whats more all of things are possible in LDR (though exposure control is a bit difficult). HDR just makes everything more realistic. The stuff about the contrast ratio of displays. The final contrast ratio of the image isnt what HDR is about either. The it will be important with newer monitors. I mean a LDR image has a contrast ration of 256:1...whats the contrast ratio of a normal CRT? LOL, if that was so important...whats the point of downloading normal JPEG previews of loast coast? Its articles like this are what make people say "WOW..another game with specular bloom...not worth a $400 graphics card". I am getting tired of reading these articles that attempt to 'dumb down' these subjects for us everyday gamers...the trouble is, most of the time theyre totally misinformed. I remember when HDR first became known (to gamers: its already known to 3D artists), most magazines explained how it was a way of displaying ever more colours and that our current 32 bit systems dont display enough colours to be realistic. Though that might be true its not what HDR is. The most basic flaw in these articles is that HDR isnt just lighting. HDR makes EVERY aspect of the games graphics more realistic (or has the potential to). Bloom, motion blur, global illumination (once its implemented in games), fogging, reflections, depth of field, ambient occlusion (once its implemented in games), transparency all become more realistic in a HDR engine. Thats before you even concider the contrast ratio of the monitor.
As very many have already pointed out, that was indeed a crap article. I don't want to spend any time quoting it and going "WTF?!", but I *do* want to link to OpenEXR, which is a file format for managing HDR images. It typically uses 16-bit floating point numbers per pixel, which seems to give a decent brightness range. It's cool to watch the same image rendered using different levels of "virtual exposure". It's by Industrial Light and Magic, which some of you might have heard of. I have, of course, no affiliation with either, just wanted to link to something relevant.
main(O){10<putchar(4^--O?77-(15&5128 >>4*O):10)&&main(2+O);}
Hello mods.
Bit-tech.net has an Article on Half Life-Lost Cost which has screenshots showing effect of HDR and link to a video.
There are four sorts of people in the world: fools, lunatics, idiots and morons. - Umberto Eco, Foucaut's pendulum.
Going outside made you realise how much we're missing? [/basement-joke]
Great post.
Thanks
Turning up the contrast and brightness on a sprite does not strike me as revolutionary. Is there something special about how they're doing it?
I work for the Department of Redundancy Department.
Paul Debevec, through his papers on acquiring low dynamic range imagery and turning that into high dynamic range imagery - and a utility to go with it coded with help from others; HDRshop, has made HDR accessible and popular.
However, 'HDR' as the storage format being used most frequently already existed in the rendering application Radiance for a long, long time before that.
In fact, -most- rendering applications render in HDR - but are forced to clip values so that you can actually output it to a regular display (e.g. your TFT) or storage format (e.g. JPG).
In fact, Valve's HDR isn't an HDR display technology. It's a partial HDR pipeline for rendering (making sure that glints of the sun are bright on water surfaces, and not dull), processing (bloom effects) and simple tone mapping a la a LUT (look into a room from a skylit outside, and the room may appear dark. Walk inside, and the room appears normal whilst the outside world will appear very bright indeed. Note that a more proper tone mapping algorithm would, besides being computationally very expensive, show the room normally and the outside world bright - but not so bright as to be blown out.)
Once we've all got HDR displays (search on Slashdot for these - I've seen them, they're awesome), we can do away with all these basic gimmicks as the human visual perceptance system will simply do all the interpreting of what should be 'correct' HDR values coming from the display.
Anyone here familiar with Gradient Domain High Dynamic Range Compression? Truly stunning imagery, but I've been having a bitch of a time actually trying to code the given algorithm. I don't suppose someone else already has? The examples look truly, truly fantastic.
Laws do not persuade just because they threaten. --Seneca
A CRT monitor is NOT limited to 8 bit RGB - it's an analog device. It responds to a voltage between 0 and 0.7 V. The back end of your graphics card typically has an 8 bit DAC, which converts the signal, and is the bottleneck. Some workstation-based graphics solutions in the past have had 10-bit DACs, but that hasn't trickled down to PCs just yet.
Don't belive me? Go watch TV... it is transmitted and processed in 10 bits, not 8. True for both SD and HDTV.
Not just eleven, but I got all the way to Special A brightness! It's like the real world, but spiffier.
HDR is in:
Seriosu Sam 2
Far Cry
From the screenshots, this looks just like the "Post-processing" used by Guild Wars since its release...
End of lesson. You may press the button.
I've played Lost Coast, and while HDR does add some great effects at times, the entire effect appears to be sampled from the center of the screen, so as you pan over objects of different brightness, the entire world eventually changes to compensate. This effect is like being outside and a small cloud passing in front of the sun momentarily, the entire world gets dimmer/brighter - and I found this to be very distracting.
Ironically, this was Valve's showcase for advanced HDR (not the lesser HDR in DoD:Source) - and in the opening title screen, the sun is so over-exposed that the word HALF in HALF-LIFE is almost unreadable. So while pre-HDR some things were hard to see because it was too dark, now you may have the same problem on the flip side being too bright. (either way, it's a quality issue)
Hopefully they will keep working on this.
Actually, there are already 16-bit high dynamic range displays using LEDs plus LCD technology. I've seen them on the exhibition floor at SIGGRAPH, and they are extremely impressive. (No, please don't ask for a picture of one :-P )
for more bits per color channel. 8 bits is clearly not enough. 12 bits (linear) is almost, but not quite enough to represent what film can, or what the human eye can see. 16 bits is enough. But not for everything...
A seond use for more bits is various image based rendering techniques. For these, 16 bits is often not enough, unless you go floating point -- and even then, 32 bit floats will produce better results. These techniques often use "blacker than black" (negative values) and "whiter than white" (values > 1.0) as intermediate results of calculations.
As a side note lamenting the demise/withering into obscurity of a once great company, starting around 1992 with the reality engine, SGI made graphics pipelines with 12 bit/channel RGBA support from end to end. It is only recently that we see support for more than 8 bits/channel in the pc world.
Ian Ameline
Age of Empires 3 does it (at least on Nvidia 6800/7800), and there have been tech demos about it available for quite some time.
Thats not good enough. I vote for mandatory vasectomies/histerectomies of all stupid people. That will work out much better.
In this particular case the "graphics people" get the credit because he's mounted a massive publicity campaign of trying to convince people that the technique is his using PR people to flood magazines and award giving institutions with press releases. I think you'll find that other graphics people don't crave publicity for other people's work quite as much. The nost heartening thing here is the number of posters, including you, pointing out that Debevec didn't actually invent anything. I've had run-ins with him myself: he claims credit for work done by me and colleagues on his web site, going so far as to add his name to something that doesn't bear his name. (Fortunately for us nobody else in the business uses his name here.)
I'm sure /.'ers know full well the effects of HDR in those rare occasions that we actually venture outside into the sun.
with screenshots and benchmarks comparing SLI and Crossfire performance.
e =Sections&file=index&req=viewarticle&artid=195&pag e=1
http://www.amdzone.com/modules.php?op=modload&nam
ignorance is bliss. googlefiberatx.com
A fairly impressive app that demonstrates HDR, motion blur, depth of field, etc. can be found here.
http://www.daionet.gr.jp/~masa/rthdribl/
My lowly graphics card can barely handle this app (Geforce 4200), but I can't wait until games support all of these features.
From all the screenshots HDR in games seems to just add the effect of the game having been videotaped with a bad camcorder that blows out either the highlights or the shadows. The funny thing is, HDR in photography tries to do the exact opposite - to capture both the highlights and the shadows and display them simultaneously using some kind of compression.
I think that technologies like this being refined are really where the future of gaming graphics is going to be for a while. While there is still a ways to go in terms of polygon count, texture and bump mapping, etc, a lot of progress has been made in these areas. I think what we will see (or hope to see anyway) offered in newer games is more support for technologies that simulate real time lighting, shadows, translucance, refraction, etc. A large part of this I think is that there are only so many resources that can be dedicated to artists now to create higher polygon count models and higher resolution more diverse textures, so things that can be done to increase the visuals of a game without having to dedicate significantly more resources to artists can vastly improve the visual quality of a game without such a significant increase in cost associated with actually crafting those visuals. With technologies such as this allowing a more realistic rendering of ourdoor scenes combined with improving algorithms for creating outdoor environments and the ability to create fractal plantlife I think that we will see a new generation of games that take the player more and more often into the less confined feeling outdoor world.
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So you're saying that this one goes to eleven?
No, it goes to #FFFFFF + 1.
Good, somebody said it because I was wondering how they were going to crank up the brightness MORE than than the brightness of my monitor. That just seemed to be impossible.
Actually #ffffff will not render the full brightness of your monitor unless you have your monitor's brightness turned all the way up. Even then it won't be full most likely since other settings can impact brightness as well. However, you're right that the article is misleading.
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So if I'm grokking the Game Developer article correctly, this technology basically consists of keeping graphics processing in the floating-point domain until the very last moment, so that the integer nature of the hardware buffers doesn't cause a loss of precision through processing stages.
It shouldn't be long until graphics accelarators have full hardware floating-point support, at which time the buffer transformations can be taken back off main CPU and memory and returned to the GPU. But doing it in software first may be the only way to give the graphics hardware manufacturers a kick in the pants, the only way of demonstrating to consumers the benefits of HDR graphics.
It's internal precision so it's not visible on screenshots. It allows for simulating the iris adjusting to the brightness level because it stores the brightness information in more than 256 shades (or 1024 in most modern engines, two overbright bits, AFAIK) so there won't be any artifacts from making stuff brighter or darker.
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You know, it masquraded as a good review, until I read stupid-assed commentary like this:
Here, we see how the bloom effect starts to put a strain on the lower memory cards. The X800 and, in particular, the 6600 GT are the most memory-limited of these cards, but ATI's X800 does significantly better than the 6600 GT.
Welcome to Video Rendering 101. Tell me class, which card will be faster, and by how much:
The 12-pipe, 400 MHz core clock card (x800), or the 8-pipe, 500 MHz core card (6600 GT).
This isn't hard. The x800, when core-limited, should produce speeds 20% faster than the 6600 GT...and lord almighty, it's a miracle: the x800 is 20% faster than the 6600 GT with full HDR enabled! It must be the EXTRA 128MB RAM, or the 40% FASTER MEMORY SUBSYSTEM. It couldn't be the damn raw pixel processing power advantage.
And now class, why would the lower-end cards in this test show greater performance loss? Is it because Here, we see how the bloom effect starts to put a strain on the lower memory cards.
HELL NO.
It's called CPU-LIMITED. You can't measure true relative performance drops becuase the scene is CPU-limited to approximately 70fps. The 6600 GT is not even able to reach the 70fps mark without HDR, and suffers noticably with it on. The other cards scale as you would expect them to according to raw core clock speed, once you turn up the pixel processing requirements (full HDR), and the 7800 GTX is STILL CPU-limited.
And then, after mentioning it CLEARLY in the breakdown above that Valve's HDR implementation supports FSAA, AND after seeing plain-as-day that the 7800 GTX is still CPU-limited, the author doesn't try out FSAA performance. A 5-year old could write the same review.
I wouldn't be surprised at all if most of the language and pictures are verbatim from a Valve-supplied press pack.
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And occasionally whores for Karma.
someone mod the parent up~
/. regular sites which supposedly write reviews, but it's actually just advertising using /. effect.. and while good reviews on other sites gets no attention, until people are posting them in the threads.
I'm really tired to see a few
Graduated neutral density filter. Cokin makes a nice kit.
...one that leaks IR like a sieve. Not good on a camera with any significant IR sensitivity, unless you like magenta skies.
This one has eleven
It is really old news. I've played Lost Coast myself last week downloaded with Steam-Down which now seems to be available at http://cs.rin.ru/forum/viewtopic.php?t=17163 I suppose it's even easier for people with legal Steam accounts. I must add, that technology showcase level is a piece of art.
Condoms will halt the spread of aids yes, however you assume that hunger is caused by overpopulation. This is simply not the case. There is plenty of food being produced in the world, more than enough to feed everyone. The problem is that the only people who get food are the people who can pay for it. Poverty causes hunger, not population pressure.
The days of the digital watch are numbered.
I believe that they're using HDR to model the non-linear sensitivity of the eye (and of photographic film). What threw me off was the talk of over- or under-exposing film. As a photographer, that doesn't make sense. It doesn't change the amount of light present in a scene. It just captures more or less of it, and thereby over- or under-exposing the film. Sure, highlights would be better represented in an under-exposed picture: you're not clipping them. Same thing for shadow detail in over-exposed pictures. All you're doing is selecting a range of levels within the scene to have properly represented, at the sacrifice of everything outside of those levels.
What didn't make sense was why expanding the range of brightness levels would change anything. Tripling the range (so that all brightness levels go from 0-3) doesn't buy you *anything* (except increased "resolution" of brightness, which isn't relevant here). This is made obvious when you then *divide* the resolution by 3 in order to display the image on the screen! And like others have said, you ain't making white any whiter than #FFFFFF...
However, the difference is that photographic paper, film, and the human eye are non-linear, and HDR gives the engine information that allows it to mimic this non-linear nature in motion effects. This is shown clearly in the difference in motion blur between HDR and non-HDR. By increaing the *internal* level of white on the windows, you allow the software to shift the level of brightness of the different objects in a non-linear way. It's that non-linear mapping of the expanded brightness range into the screen brightness space that is different.
It also sounds like they are not doing this by simply increasing the range of brightness and using some non-linear function to map the expanded range into the "normal" range of the monitor, though it seems to me that this would be the most accurate way of doing this. According to the Ars article, it sounds like this is being done with a "radiosity channel" (kind of like an alpha channel). Of course, my guess is that this is more for performance than for effect: for those things that don't need the enhanced radiosity, you can skip the whole non-linear portion and just map it directly. I would assume that they would save a relatively small percentage of values at the top end only for highly radious (is that right? radial?) areas, and map the non-radious images into the rest of the range. However, I have no idea how this is actually done, or even if my guesses are correct. I'd love to know from someone who has a better understanding where I went wrong! :)
Interesting. It seems to me that HDR is kind of like motion blur for brightness. However, I wonder if, like motion blur, it's an exaggeration (or outright fabrication) of something we don't really see? For example, motion blur as seen by a camera is *way* greater than motion blur as seen by the eye. A runner, for example, running perpendicular to a photographer will blur with anything but a relatively high shutter speed, but they don't look blurry to the eye as they run by a spectator. I have a feeling that the effects generated by HDR may also be an over-exaggeration of what the human eye actually sees, rather than what film actually records. While it matches what a camera might see, it doesn't match what the eye would actually see in the camera's place. Or, for that matter, a different camera, with different film, and a different shutter speed! :)
But whatever. If people think it "looks" better, even if they're wrong, who cares? Go for it! :)
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His definition of radiosity is a joke. Can anyone just get an article linked on slashdot?
...and have you ever noticed how photographs - particularly artistic ones by professionals - don't actually look anything like what we see with our eyes?
The bad camcorder is a much closer representation of what we really see than a carefully composed photgraph.
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