The first, and most commonly used processor is the pdf_run_processor. This processor has the effect of interpreting the incoming operators and turning them into device calls (i.e. graphical objects rendered on a page).
When using the standard fz_run_page (and similar) function(s) this is the pdf_processor that is used automatically. It can still be useful to create these manually, especially when coupling them with a pdf_filter_processor (or similar).
Such processors can be created using:
The component parts of this processor are generally functions named pdf_run_..., and frequently call back into the main pdf interpreter (to handle nested content streams as found in XObjects etc).