Object edge point filtering system for machine vision

Abstract

A system and method for filtering edge points in an edge image represented by an array of edge image coordinates each having an edge point magnitude. An edge map array is formed of edge map coordinates each assigned one of three edge indicator values indicative of the relationship between the corresponding edge image coordinate edge point magnitude and two preselected edge magnitude thresholds. An output edge point array is formed of output edge point coordinates to indicate those edge image coordinates and corresponding object image pixels that are validated by the system as being associated with likely object edge points. This is accomplished by constructing a first address stack to track memory addresses at which edge map coordinate values are stored and constructing a second address stack to track memory addresses at which output edge point coordinate values are stored as the output edge point array is constructed. Selected output edge point coordinates are assigned with a preselected edge point value by first scanning the edge map array for edge coordinates assigned the first preselected edge indicator value and, using the stacks to keep track of the addresses of these coordinates, neighboring edge map coordinates are examined for any edge map coordinates assigned with either the first or second preselected edge indicator values. The address of edge map coordinates found to be assigned with either the first or second preselected edge indicator values are then tracked by the stacks.