An image resource, returned by one of the image creation functions, such as imagecreatetruecolor().
The path to save the file to. If not set or
NULL, the raw image stream
will be outputted directly.
IMG_GD2_COMPRESSED. Default is
This function requires GD 2.0.1 or later (2.0.28 or later is recommended).
The GD2 format is commonly used to allow fast loading of parts of images. Note that the GD2 format is only usable in GD2-compatible applications.