Distance estimator

For the code generator, I think that you use for color gradient a "smooth escape time fomula".
Did you ever try a distance estimator formula ? (it is twice slower, but with the same amount of iterates, it provides a better definition near M or Julia. I tried it in the past: it is quite compatible with your algorithm of variable detail level and should improve the image near the boundary, by adding anti-aliasing and resolution).

Re: Distance estimator

I haven't tried it in Fraqtive; speed was my priority, even at the cost of precision and quality.