Method and system for color film separation preprocess using electronic object-based choking and spreading procedures including object combining operations

A computer system 100 for production of ink separations from an object-based print pre-process apparatus using a page description language. The print pre-process system facilitates creation of object spreads for any combination or configuration of objects on the rendered page. For each object on a rendered page, the computer system 100 makes use of a spread table to determine spread incidences. For each spread incidence, the computer system generates set union, intersection and difference for spreading, receiving, and obstructing objects by use of a modified Weiler algorithm. The modified Weiler algorithm creates a simplified graph of contour histories providing a visible portion of the spread object. The visible object is strokable within a clipped window set to the receiving object. The stroke color and width, set by the spread table, can be knockout print or overprint.