Halley Lace B Chain

Halley's method applied to f(z) = (z^4 - 1)(z^4 + 16) = z^8 + 15z^4 - 16, windowed 1.2 wide on the diagonal arm centred at 0.9 + 0.9i. Halley's iteration is a rational map of degree 2n - 1 where Newton's is degree n, which is what grows the chain of scalloped bubbles crossing the frame. Each of the eight roots owns one hue, and brightness follows the smooth escape time nu = k + log_3(ln tol / ln|f|).