code: public byte[] drawTileData(short[] pixelValues, int tileWidth,
  			int tileHeight) {
  		BufferedImage image = drawTile(pixelValues, tileWidth, tileHeight);
  		byte[] bytes = getImageBytes(image);
  		return bytes;
  	}
docs: Draw a coverage data image tile and format as PNG bytes from the flat
  array of "unsigned short" pixel values of length tileWidth * tileHeight
  where each pixel is at: (y * tileWidth) + x
  
  @param pixelValues
  "unsigned short" pixel values of length tileWidth * tileHeight
  @param tileWidth
  tile width
  @param tileHeight
  tile height
  @return coverage data image tile bytes