Efficient imposition of arbitrary postscript.RTM. files without preprocessing by defining a virtual device that specifies a desired position of a page on an output device while redefining postscript save and restore operators

A method of imposing selected pages defined in a sequence of page descriptions included in a PostScript.RTM. file, wherein the selected pages are interpreted by an interpreter and may be transmitted to a raster memory for rendering on a flat by an output device, comprising the steps of:

• a) determining whether a current page from the sequence of page descriptions is a selected page to be rendered on the flat;
• b) if the current page is a selected page,
• i) defining a virtual device as the output device for the selected page, wherein the virtual device specifies an area in the raster memory for positioning the selected page on the flat;
• and
• ii) interpreting the selected page
• c) if the current page is not a selected page,
• i) determining a next page in the sequence of page descriptions that is a selected page to be rendered on the flat;
• ii) defining the virtual device for the next selected page as the output device for the non-selected page;
• and
• iii) interpreting the non-selected page;
• d) redefining a PostScript.RTM. save operator to save a definition of the virtual device;
• and
• e) redefining a PostScript.RTM. restore operator to apply an accumulation of operations applied on the saved definition of the virtual device to a current virtual device.