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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.'"
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
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.
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 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 "Mega-Bass" button doesn't usually give you "more bass than the musician originally intended," it usually just gives you about the same level they intended because the types of stereos with that button generally don't reproduce as much bass as the $1,000/piece reference monitors in the studio that the musicians mastered from.
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
Ah, I see you have never designed any graphics related software or hardware whatsoever. While it is not possible to make truly unbounded colour brightness levels in graphics, it can be approximated with floating point arithmatic, clever gamma curves or just really big integers (32 bits per channel or so). All of which take a lot of processing power, a lot of memory or both. It has only been a recent thing that graphics card manufacturers have had the powerful technology at their disposal to even think about this, let alone implement these techniques. If we had not had the hack known as 24 bit colour for the last twenty years we would have had nothing.
Now I come to think about it, the author of that artical doesn't know much better: Radiosity is a way of rendering a scene using only visible light sources WTF? Radiosity is a way of rendering a scene by taking into account light bouncing between surfaces, being absorbed by surfaces and emitted at different wavelengths etc. Pretty much the oposite of what it describes since real radiosity will create an effect similar to ambient lighting. The artical is written by idiots for idiots.
When Argumentum ad Hominem falls short, try Argumentum ad Matrem
"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.
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.