libiptcdata is a library, written in C, for manipulating the International
Press Telecommunications Council (IPTC) metadata stored within multimedia files
such as images.  This metadata can include captions and keywords, often used by
popular photo management applications.  The library provides routines for
parsing, viewing, modifying, and saving this metadata.  The libiptcdata
package also includes a command-line utility, iptc, for editing IPTC data in
JPEG files.

WWW: http://libiptcdata.sourceforge.net/