code: public byte[] drawTileData(short[][] pixelValues) {
  		BufferedImage image = drawTile(pixelValues);
  		byte[] bytes = getImageBytes(image);
  		return bytes;
  	}
docs: Draw a coverage data tile and format as PNG bytes from the double array
  of "unsigned short" pixel values formatted as short[row][width]
  
  @param pixelValues
  "unsigned short" pixel values as [row][width]
  @return coverage data image tile bytes