http://www.php.net/manual/en/ref.pdf.php
contains this:
LXXV. PDF functions
Introduction
The PDF functions in PHP can create PDF files using the PDFlib library created by Thomas Merz. PDFlib is available for download at http://www.pdflib.com/pdflib/index.html, but requires that you purchase a license for commercial use. The JPEG and TIFF libraries are required to compile this extension. Please see the PDFlib installation section for more information about compiling PDF support into PHP.
