docs: public static void flipHorizontal( GrayS32 input ) {
  		int w2 = input.width/2;
  
  		for( int y = 0; y < input.height; y++ ) {
  			int index1 = input.getStartIndex() + y * input.getStride();
  			int index2 = index1 + input.width-1;
  
  			int end = index1 + w2;
  
  			while( index1 < end ) {
  				int tmp = input.data[index1];
  				input.data[index1++] = input.data[index2];
  				input.data[index2--] = (int)tmp;
  			}
  		}
  	}