code: public static <T extends ImageGray<T>> void down(Planar<T> input ,
  												  int sampleWidth , Planar<T> output )
  	{
  		for( int band = 0; band < input.getNumBands(); band++ ) {
  			down(input.getBand(band), sampleWidth, output.getBand(band));
  		}
  	}
docs: Down samples a planar image.  Type checking is done at runtime.
  
  @param input Input image. Not modified.
  @param sampleWidth Width of square region.
  @param output Output image. Modified.