code: public static GrayF32 average( InterleavedF32 input , GrayF32 output ) {
  		if (output == null) {
  			output = new GrayF32(input.width, input.height);
  		} else {
  			output.reshape(input.width,input.height);
  		}
  
  		if( BoofConcurrency.USE_CONCURRENT ) {
  			ConvertInterleavedToSingle_MT.average(input,output);
  		} else {
  			ConvertInterleavedToSingle.average(input,output);
  		}
  
  		return output;
  	}
docs: Converts a {@link InterleavedF32} into a {@link GrayF32} by computing the average value of each pixel
  across all the bands.
  
  @param input (Input) The ImageInterleaved that is being converted. Not modified.
  @param output (Optional) The single band output image.  If null a new image is created. Modified.
  @return Converted image.