Frame rate up-conversion using trilateral filtering

Frame rate up-conversion (FRUC) can enhance the visual quality of low frame rate video presented on liquid crystal display. To minimize the difference between a reference block and an interpolated block, an effective FRUC algorithm partitions a large block into several sub-blocks of smaller size and estimates their motions. Motion estimation searches for the block which has the minimum difference (cost) with the processed block in terms of some block matching distortion and motion discontinuity. As convexity and convergence of the cost function are not guaranteed, the computational cost for such motion estimation is usually extensive or unpredictable. In our proposed FRUC method, the two predictions of a frame to be interpolated are generated through shifting its nearest neighbor frames in the previous and following directions with the motion vectors estimated between them. The initial interpolated frame and its pixel's reliability are subsequently estimated from these two predictions. We then apply a trilateral filter on the initial prediction to correct the unreliable pixels and to restore the missing pixels. Our proposed method not only reduces the computation for refining motion vectors, but also suppresses the interpolation noises and misregistration errors. We have conducted extensive experiments and the results show that the proposed algorithm outperforms the existing methods with better objective and subjective visual quality, and achieves about 3 dB on-average peak signal-to-noise ratio improvement.