static BufferedImage grayImageFromIBWIntegralImage(IBWIntegralImage
img) {
int w = img.getWidth(), h = img.getHeight();
byte[] pixels = new[w*h];
int pixel = img.getPixelBrightness(x, y);
ifdef grayImageFromIBWIntegralImage_debug
if (x == 0 && y == 0) print(+pixel);
pixels[i++] = clampToUByte(pixel;
ret newGrayBufferedImage(w, h, pixels);