Low bit rate video sequence coding artifact removal

The picture quality of video frames encoded at very low-bit rates often suffers from both blocking and ringing artifacts. We present two post-processing methods to mitigate the visual quality degradation caused by these artifacts. To reduce the blocking artifact of decoded images, we substitute IDCT for the lapped orthogonal transform embedded inverse discrete cosine transform (le-IDCT). On the other hand, we post-process the decoded video frames using a nonlinear robust filter to reduce the ringing artifact. Extensive simulation results indicated significant improvement in both objective and subjective visual qualities. The computation overhead incurred due to these quality enhancement operations is quite moderate, and can be easily optimized to achieve real-time operation.