static float wideBlack_maxBrightness = 0.1f;

static Range wideBlack(RGBImage img, int x, int y) {
  int w = img.w();
  int x1 = x, x2 = x;
  while (x1 > 0 && img.getPixel(x1-1, y).getBrightness() < wideBlack_maxBrightness) --x1;
  while (x2 < w && img.getPixel(x2, y).getBrightness() < wideBlack_maxBrightness) ++x2;
  ret new Range(x1, x2);
}