Those who are not proponents of 64-bit color are also often quick to point out that current monitors only have approximately 32 bits of resolution, and roughly a 10-bit color component. While true, Carmack believes that this is beyond the point. The benefits of 64-bit color, he feels, manifest themselves in other ways.
He went on to explain that "While a monitor may only display this, say, 10-bit resolution on there, the human eye is capable of perceiving well over a range of 64,000 [colors]... like the difference between these lights that are shining right in my eyes here, and the floor... sitting down there, between the aisles. That's a difference of hundreds of thousands of levels."
"The way you should be calculating all graphics... the way it ought to be done is: you're basically counting out photons that are, you know, imprinted on a surface. Lights spray out a whole lot of photons, that are collected on surfaces. If you're doing things really right, you have an inverse square falloff, and you have a radiosity map, and all this... So what we want to do is do all of this calculation the right way, and then... we know at the end that it's going to be going on to some... not exactly optimal solution that we want on the monitors there. But there's still a lot of benefit to gain by doing all of the intermediate calculations the way you really should do it. "
He explained that the benefit to more realistic lighting is that it reduces the dimming effect that the various "crappy approximations" that engine coders have had to use until now often produce. This dimming effect is often a source of frustration for artists and content designers, as the piece of artwork they create in photoshop can (and frequently does) look vastly different from what is rendered out in realtime by the game. While Doom does not fully calculate light the way Carmack would like, it is capable of specifying lights that are much brighter than the normal range. The downside of this capability is that, without radiosity bounces, it can make the edges much more harsh.
"But... with the next generation stuff, all you really have to do is basically say 'this light is arbitrarily bright,' and everything just kind of magically works."
