Musings on discernible display resolution (color and geometry)

Abbreviations
Smallest Discernible Solid Angle (SDSA): 0.01x0.01deg FOV. This is approximately the smallest area a human eye can discern.

Quadruple color resolution
Ideally 1 pixel would take up 1 SDSA, however, if a square of 4 pixels takes up 1 SDSA it is not entirely wasteful. Those pixels would color average together, effectively quadrupling the color resolution. For example, instead of just color steps of 4, you now have color steps of 1.

Increased pixel density requires more color depth
Generally the closer spots are on a surface the less color difference there is. Now with 8.3 megapixel displays this is very important. To be able to express this color difference, high color resolution is required (30bit or 36bit instead of just 24bit.) Otherwise those pixels would look the same and blend into apparent larger pixels. Also contrast (difference between lowest to highest brightness) is important, it must be high enough so that humans can detect the difference.