The OPI rendering module is needed for your backend server (Windows only). It translates uploaded XML pages (containing OPI information) on-the-fly to the final PDF pages. Usually, pages are uploaded as PDF directly, but in the case of OPI, the page can only be finalized by the backend. OPI images are defined by the designer of the product layout file. Calling convention:
PubRender.exe /in:"c:\orders\0212\page_002.dtp" /img:"C:\opi-images" /out:"c:\orders\0212\page_002.pdf"
The high resolution images defined by the /img command line parameter the must lie in a folder of the backend server.
The OPI feature has meanwhile been replaced by crypted resource images, which are replaced shortly before upload.