Lighting: Dynamic Range

• the real world has much, much higher dynamic range than computers currently allow
• it would be great to model the actual light values of each objects, in realistic units, then dynamically map a clipped range of values onto the actually 0-255 range of the output display.
• this would allow for day/night rendering of emissive sources (sun, moon, stars, streetlights etc.) in as realistic a fashion as possible
• this is still a new area of research
• the abbreviation is usually "HDR" or "HDRI" for High Dynamic Range Images
• Johan Hammes's Dynamic Eye Modeling
  • visual examples of his approach to the "glare" effect of the human eye's reaction to light
• Gregory Ward Larson has done tons of work in this field
  • High Dynamic Range Images (pdf)
  • Overcoming Gamut and Dynamic Range Limitations in Digital Images (pdf)
  • A Visibility Matching Tone Reproduction Operator for High Dynamic Range Scenes (pdf)
  • an 8-bit display could be fine if we could just have >10 bits in the rendering hardware and a realtime histogram-based mapping to the display like in the above tone-reproduction paper
• Paul Debevec has done lots of work in this area
  • many, many academic papers on HDR imaging
  • HDR Shop is a program for manipulating HDR images
• Jack Tumblin says "Computer graphics rendering should mimic human vision, not film cameras; it should include more of the light-dependent changes in the way we see."
  • GVU Technical Report 98-22: Two Methods for Display of High Contrast Images
• HDRI & Luminance space is a overview and explanation in layman's terms
• consider that TV/Video material on CRTs has the same brightness range as a computer screen, yet people find that level of realism convincing: with the right combination of level balancing and tricks like lens flare, it is therefore logically possible to reproduce the effect of that extra brightness without actually emitting more photons.
• OpenGL 1.2 added some interesting sounding imaging extensions which may provide some hardware assistance for histogram functions
• Exposure by Hugo Elias
  • discusses the dynamic range problem by analogy to photography
• input from Deanan: "I've done some 10/12 bit stuff on the onyx which was really nice.  It might be possible to do some realtime histogram stuff but I've not timed how fast the OpenGL histogram extensions are."