FractalBrightness

Mandelbrot set, centered at -0.74295085 + 0.139442616666667i, radius 0.001, 5000 iterations.

Pixels are sorted by number of iterations (plus a smoothing factor based on final distance to the origin), and matched to colors, sorted by lightness.

Note that I used lightness in CIE color space. This reduces the noise and increases the vibrancy compared to using lightness as a linear combination of R, G, B values.