docs: public static void flipVertical( GrayS32 input ) {
  		int h2 = input.height/2;
  
  		for( int y = 0; y < h2; y++ ) {
  			int index1 = input.getStartIndex() + y * input.getStride();
  			int index2 = input.getStartIndex() + (input.height - y - 1) * input.getStride();
  
  			int end = index1 + input.width;
  
  			while( index1 < end ) {
  				int tmp = input.data[index1];
  				input.data[index1++] = input.data[index2];
  				input.data[index2++] = (int)tmp;
  			}
  		}
  	}