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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.'"
You've missed the point - though I can't blame you, judging by the blurb the article was less than pedagogical when trying to explain HDR.
This isn't about altering what any "author" intended. On the contrary, HDR is a new tool which lets the "author" do what's intended more easily, assuming what's intended is to achieve realistic lighting in the rendered scenes. Try Anandtech's recent article on the topic, they explain it very well.
-- If no truths are spoken then no lies can hide --
It's a lot more than just a bass boost, since it's not just a brightness increase, but an increase in the range of brightness, allowing for very high contrast. If you go back and look at a Source game without HDR after seeing HDR for awhile, it looks like it has a dark film over it, similar to a digital camera picture looks before being run through auto-contrast in Photoshop.
WHO NEEDS SHIFT WHEN YOU HAVE CAPSLOCK/ DAMN1
I think, if you want to be precise, what Valve did in Lost Coast should be called Paul Debevec's High Dynamic Range.
except that the authors are the ones using and implementing hdr. If it was a mod to a game already released I would agree, but the case for most games is going to be to add this as a feature. So I guess to include your example, maybe if Trent Reznor released some track that had mega bass activated through effects that would make sense, but really, im not sure that its the greatest analogy. ;/
Think of it this way:
When you wake up at night and you can see the room in nearly pitch black, things appear to be as bright as your room in the morning with the shades closed. Actually, the room in the morning is 1000 times brighter. The "author" of the real world (God?) "intended" the room to be 1000 times brighter by slamming 1000 times more protons onto your retina, but your brain normalizes things to make the world easier to comprehend.
Now, when you are playing a video game, and you go into a dark room with almost no light, current algorithms don't make it easier to see anything - they present you with a black screen. When you walk out into the sunlight, you get a white screen. This is now the way our brain sees the world, and makes the experience less realistic.
Audio, on the other hand, can be presented to us nearly perfectly. My headphones can range from 20 Hz to 20 KHz, all the frequencies our ears can hear. The mega-bass thing is therefore useless if you have a decent pair of speakers.
I guess my point can be summed up with this example: you can make a really good set of speakers as loud as an airplane if you want. Your monitor, however, cannot shine the sun in your eyes.
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.
HDR is no more a hack than showing natural video on a TV. Sure, the screen has less dynamic range than reality, and you need a mapping function (exposure settings when working with natural light) to display it in a sensible way, but it still pays off hugely to do all the lighting in the scene without regard for that, just as reality dioes.
The alternative (the traditional 8-bit path) corresponds to a reality where no light can be brighter than the white of the monitor", including when adding up light from several sources! Trying to get real photorealism that way is a lost cause. There's a reason why even holywood CG until recently always looked really 'flat', except in very dark scenes (lower dynamic range to model)
And for the record: those blooming effects are not part of HDR. They are simply post-process SFX, emulating scattering and other effects in the eye and in cameras. Sure, you couldn't do them really well without HDR, so they're a nice poster child for what it lets you do. But they are not what makes the process HDR.
Volumetric effects are of course not inherently HDR either; they've eben around a long time, just too heavy to do for most games to bother with until now, and looking much better with HDR (and bloom).
sudo ergo sum
That is the worst explenation of HDR I have ever seen. Clearly missed the point.
sudo ergo sum
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.