A technique is presented for aggregating edge points into polylines which can effectively represent object contours. The technique is based on a new formulation of Hough transform (HT) for detection of line segments. The space requirement of the HT is brought down by considering a different parameterization of straight lines. In this method, the process of edge linking and boundary approximation are combined into a single algorithm. Consequently, the scheme is computationally more efficient than the classical boundary approximation techniques which require a separate edge linking algorithm for preparing their input-the linked list of edge points. Experimental results presented here highlight the effectiveness of this method for approximating object boundaries of polygonal as well as curved shapes present in the images of complex multi-object scenes even in the presence of noise. Further, the parallel algorithm proposed herein for implementation of this technique makes it an ideal choice for real time applications. © 1993.