void pdf_put_image(int pdf document, int image);
The PDF_put_image function places an image in the PDF file without showing it. The stored image can be displayed with the PDF_execute_image() function as many times as needed. This is useful when using the same image multiple times in order to keep the file size small. Using PDF_put_image() and PDF_execute_image() is highly recommended for larger images (several kb) if they show up more than once in the document.
Note: This function has become meaningless with version 2.01 of pdflib. It will just output a warning.