srecord noeq RawBufferedImageDistance_sameSize(BufferedImage img1,
  BufferedImage img2) {
  settable long stoppingValue = Int.MAX_VALUE;
  int w, h;
  int x, y; // where we stopped calculating
  long sum;
  
  bool completed() { ret w != 0 && x == w && y == h; }
  
  long get() {
    int w = this.w = img1.getWidth(), h = this.h = img1.getHeight();
    assertSameSize(img1, img2);
  
    var gp1 = grabbableIntPixels_fastOrSlow(img1);
    var gp2 = grabbableIntPixels_fastOrSlow(img2);
    
    int iPixels1 = gp1.offset, iPixels2 = gp2.offset;
    int[] pixels1 = gp1.data, pixels2 = gp2.data;
    long sum = 0;
    
    for y to h: {
      for x to w: {
        sum += rawRGBDiff(
          pixels1[iPixels1+x],
          pixels2[iPixels2+x]);
          
        // cancel if difference out of interest range
        if (sum > stoppingValue) {
          this.x = x; this.y = y;
          this.sum = sum;
          ret sum;
        }
      }
      
      iPixels1 += gp1.scanlineStride;
      iPixels2 += gp2.scanlineStride;
    }
  
    this.x = w; this.y = h;
    ret this.sum = sum;
  }
}