docs: public Pixel[] pixels(int x, int y, int w, int h) {
          Pixel[] pixels = new Pixel[w * h];
          int k = 0;
          for (int y1 = y; y1 < y + h; y1++) {
              for (int x1 = x; x1 < x + w; x1++) {
                  pixels[k++] = pixel(x1, y1);
              }
          }
          return pixels;
      }