Rate-Distortion Optimal Shape Coding Using B-Spline Snakes
نویسندگان
چکیده
This paper addresses the problem of joint rate-distortion optimization of spline curves for optimal video object shape coding. It proposes a B-spline snake model which minimizes rate-distortion energy to find optimal spline coefficients. A continous model of a contour distortion is used which models the shape reconstruction error. A continous model of a coding bitrate is based on the relative intra-frame addressing of control points and includes linear prediction, quantization and arithmetic encoding of the prediction error. The models enable continuos gradient optimization of snake control points. A global snake energy minimization algorithm is defined which includes snake coefficient optimization as well as quantization step optimization and knot insertion strategy. This results in finding an optimal number and positions of spline control points and optimal quantizer parameters for the given rate constraint.
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