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.'"

Comments

Re:Sounds better than "turning up the contrast"

[GameMaster]

Actually, HDR rendering has nothing to do with the contrast limits of the physical display device. Even the best display devices have limits on how bright they can get. To some extent this is a good thing, if monitors ever became capable to representing something like the sun at true brightness then we'd have to worry about in-game bugs causing eye damage by setting the display brightness too high.

HDR is a technique that uses floating point values rather than integers to represent luminance values within the pre-rendered scene. These values are then compared to each other before the scene is actually rendered and the luminance of the individual portions of the rendered scene are assigned based on the relative brightness of each light source when compared to each others. Basically, if you have a bright floodlight and a small flashlight visible to the camera the floodlight should vastly overpower the flashlight and should probably max out the brightness of the physical display device. However, if you move the camera angle up a little bit and include the sun in the scene, then HDR would dynamically darken all the other lights in order to make the sun look like the brightest light source and the sun would then have taken the highest brightness setting of the display device.

Another effect that is created using HDR is glare. An example of this in the real world is when you look directly at a bright light source, like the sun (I don't really recommend trying this out with the sun because it might cause eye damage but a flashlight or a light bulb should work too). The light source tends to look larger than it actually is because the light drowns out anything around it.

HDR rendering has been hardware accelerated on the new last few generations of video cards, but only recently has performance been acceptable enough to actually implement into a commercial game.

-GameMaster