docs: public void update( ImageGray image ) {
  		if( approximateHistogram ) {
  			for (int i = 0; i < bins.length; i++)
  				bins[i] = 0;
  
  			if (image instanceof GrayF32)
  				update((GrayF32) image);
  			else if (GrayI.class.isAssignableFrom(image.getClass()))
  				update((GrayI) image);
  			else
  				throw new IllegalArgumentException("Image type not yet supported");
  		} else {
  			GImageStatistics.histogram(image,0,bins);
  		}
  	}