sinterface UpdatableImage extends Meta implements IIntegralImage {
  int w, h;
  RegisteredReference<IIntegralImage> contents = new(this);
  
  public int getWidth() { ret w; }
  public int getHeight() { ret h; }

  public double getIntegralValue(int x, int y, int channel) {
    ret contents.get(x, y, channel);
  }
    
  public double getIntegralValue(int x, int y) {
    ret contents.get(x, y);
  }
}