if(w <= 0 || h <= 0) throw new IllegalArgumentException("width (=" + w + ") and height (=" + h + ") must be > 0");
  public final WritableRaster createCompatibleWritableRaster(int w, int h)  {		SampleModel sm = createCompatibleSampleModel(w, h);		Point origin = new Point(0, 0);		return Raster.createWritableRaster(sm, origin);	}