Color and Human Perception Homework Solutions

1. Imagine that you are able to obtain a super huge, high resolution display that measured 10'x10' and used a frame buffer of 8192 by 8192 pixels. Since the frame buffer is so large, a color lookup table is used to limit the size of memory needed. Each pixel coordinate of the frame buffer is given 8 bits to index into a table with 256 possible 24 bit colors. (Total memory = 64 MBytes + 768 Bytes.) Imagine that, in addition to this amazing feat of engineering, you had an eye-tracking device the could precisely determine where a viewer a few feet from the screen was looking at any point in time. Finally, imagine that every time the viewer changed where she was looking on the screen, the application she was using could generate a new image to display to the screen. How might the application exploit an understanding of how the eye works to provide an image to the one viewer that appears to have many more different colors than the 256 possible?

With such a large display, with the viewer sitting fairly close to it, it would be possible to vary the number of colors displayed to the view depending on how far each particular pixel was from where the viewer was actually looking, without the viewer noticing. One could imagine three ranges from the point on the screen at which the view is looking. Within a certain range from that point, you would want to have as many different colors as possible, although you would like more variations in red and green than blue (since the human perceptual system doesn't distinguish as many shades of blue). Further than that, but not quite to the edge of the display, less colors could be used, although the number of colors that differ in amounts of blue should be more even with the number of colors that differ in the amounts of red and green. Finally, in the outer range, you could get away with using only shades of gray and black. Note that the actual ranges with which this technique would work would depend on the person, and this display would have to have a phenomenal refresh rate, as the perceptual system easily picks up "flicker" in the periphery.