Well, this seems certainly straight forward from an information theory angle of view:
- Each pixel represents one bit.
- Hence, we should try to increase information entropy.
That's all there is to it? Certainly not, since we are creating something for human consumption. There are a couple of other factors:
- The way the eye processes patterns: lateral inhibition [1]
- The way the eye processes colours: photopic vision [2]
- The way the brain interprets patterns
- The way the brain can actually interpret ingoing information.
I don't have an answer to all of these. But is pretty certain that maximizing entropy of a binary pattern is not equivalent to optimiziung reading speed.