cairo_ps_surface_create ()

cairo_surface_t* cairo_ps_surface_create    (const char *filename,
                                             double width_in_points,
                                             double height_in_points);

cairo_ps_surface_create_for_stream ()

cairo_surface_t* cairo_ps_surface_create_for_stream
                                            (cairo_write_func_t write_func,
                                             void *closure,
                                             double width_in_points,
                                             double height_in_points);

cairo_ps_surface_set_dpi ()

void        cairo_ps_surface_set_dpi        (cairo_surface_t *surface,
                                             double x_dpi,
                                             double y_dpi);

Set horizontal and vertical resolution for image fallbacks. When the postscript backend needs to fall back to image overlays, it will use this resolution.