This paper introduces a new method of converting interlaced video to a progressively scanned video and image. The new method is derived from Bayesian framework with the spatial-temporal smoothness constraint and the MAP is done by minimizing the energy functional. The half-quadratic regularization method is used to solve the corresponding partial differential equations (PDEs). This approach gives the improved results over the conventional de-interlacing methods.Two criteria are proposed in the paper, and they can be used to evaluate the performance of the de-interlacing algorithms.