Rate distortion optimal contour compression using cubic B-splines

Object contours resulting from segmenting images or video frames can be efficiently encoded using B-spline functions. An unsolved problem is how to divide a given contour into segments such that the resulting compression is optimal in rate-distortion sense. In this paper we describe two techniques for finding a close-to-optimal knot assignment. The first technique prunes an accurate B-splines approximation until the desired rate is achieved. The second technique analyzes the curvature function of the original contour to obtain a suboptimal knot assignment. The resulting algorithms are compared experimentally.