sclass IIPadded extends Meta implements IIntegralImage {
  int w, h;
  Rect innerRect;
  RGB paddingColor = RGB(Color.black);
  IIntegralImage inner;
  
  *(IIntegralImage *inner, int *w, int *h, int innerX1, int innerX2) {
    innerRect = rect(innerX1, innerX2, inner.getWidth(), inner.getHeight());
  }
  
  public int getWidth() { ret w; }
  public int getHeight() { ret h; }

  // get pixel sum from 0, 0 through x, y (inclusively)
  public double getIntegralValue(int x, int y, int channel) {
    int pad = paddingColor.getInt(channel);
    if (y < innerY1)
      if (x < innerX1)
        ret pad*(x+1)*(y+1);
      else
        ret pad*(x+1)
    if (x < splitPoint)
      ret a->getIntegralValue(x, y, channel);
    else ret
      a->getIntegralValue(splitPoint, y, channel)
        + b->getIntegralValue(x-splitPoint, y, channel);
  }
}