Graphic images can be written to files in several formats, using
All platforms can write at least BMP, JPG, PNG and TIFF files. Call the function
with optional argument
to list the formats that the current platform supports for writing.
On Microsoft Windows and Cocoa you can also write GIF files, while on GTK+ you can also write ICO and CUR (cursor) files. The cursor files that are written with GTK+ can be used on Windows and Cocoa, although on Cocoa it does not recognize the hot-spot in a CUR file.
There is a simple example of writing a PNG image here:
CAPI User Guide (Unix version) - 30 Aug 2011