// f should return a value between 0 and 1 (will be clamped for you)
static FloatBWImage floatBWImageFromFunction(int w, int h default w, IF2_IntInt_Double f) {
  FloatBWImage img = new(w, h);
  for y to h:
    for x to w:
      img.setPixel(x, y, (float) f.get(x, y));
  ret img;
}

static FloatBWImage floatBWImageFromFunction(int w, int h default w, IF0<Double> f) {
  ret floatBWImageFromFunction(w, (x, y) -> f!);
}

Began life as a copy of #1026933