docs: public static void fillRectangle(GrayF64 img, double value, int x0, int y0, int width, int height) {
  		int x1 = x0 + width;
  		int y1 = y0 + height;
  
  		if( x0 < 0 ) x0 = 0; if( x1 > img.width ) x1 = img.width;
  		if( y0 < 0 ) y0 = 0; if( y1 > img.height ) y1 = img.height;
  
  		for (int y = y0; y < y1; y++) {
  			for (int x = x0; x < x1; x++) {
  				img.set(x, y, value);
  			}
  		}
  	}