This paper presents pixel-based and region-based parametric motion segmentation methods for robust motion segmentation with the goal of aligning motion boundaries with those of real objects in a scene. We first describe a two-step iterative procedure for parametric motion segmentation by either motion-vector or motion-compensated intensity matching. We next present a region-based extension of this method, whereby all pixels within a predefined spatial region are assigned the same motion label. These predefined regions may be fixed-or variable-size blocks or arbitrary-shaped areas defined by color or texture uniformity. A particular combination of these pixel-based and region-based methods is then proposed as a complete algorithm to obtain the best possible segmentation results on a variety of image sequences. Experimental results showing the benefits of the proposed scheme are provided. (C) 1998 Academic Press.