code: public static void down(GrayU8 input , int sampleWidth , GrayI8 output ) {
  		if( sampleWidth == 2 ) {
  			if(BoofConcurrency.USE_CONCURRENT ) {
  				ImplAverageDownSample2_MT.down(input, output);
  			} else {
  				ImplAverageDownSample2.down(input, output);
  			}
  		} else {
  			if(BoofConcurrency.USE_CONCURRENT ) {
  				ImplAverageDownSampleN_MT.down(input, sampleWidth, output);
  			} else {
  				ImplAverageDownSampleN.down(input, sampleWidth, output);
  			}
  		}
  	}
docs: Down samples the image.
  
  @param input Input image. Not modified.
  @param sampleWidth Width of square region.
  @param output Output image. Modified.