A tile is an image used to fill an area with a repeated pattern. Any GD image can be used as a tile, and by setting the transparent color index of the tile image with imagecolortransparent(), a tile allows certain parts of the underlying area to shine through can be created.
You need not take special action when you are finished with a tile, but if you
destroy the tile image, you must not use the
color until you have set a new tile image!
An image resource, returned by one of the image creation functions, such as imagecreatetruecolor().
The image resource to be used as a tile