I implemented

> "Adaptive filtering for progressive Monte Carlo image rendering" (2000) by Frank Suykens , Yves D. Willems
> https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.142.2366 (links to 2.4MB PDF)

for a toy #NonLinear #IFS (#IteratedFunctionSystem) #FractalFlame renderer, following the plan of

> "The Fractal Flame Algorithm" (2003-2008) by Scott Draves, Erik Reckase
> https://flam3.com/flame_draves.pdf (22MB(!) PDF)

Seems to work well!

I haven't yet optimized the first pass with fixed radius, if I use a separated blur kernel (just blur horizontally then blur the result vertically) it should be a lot faster for most images (for sparse dots it might be slower, but they're boring).