Temporal Wavelet Transform-Based Low-Complexity Perceptual Quality Enhancement of Compressed Video

The past few years have witnessed a great success in applying deep learning to enhance the perceptual quality of compressed video. These methods usually perform frame-by-frame quality enhancement, incurring high computational complexity. Low-complexity perceptual quality enhancement is addressed in this paper, motivated by the observation of temporal correlations among video frames. We propose to decompose video content into temporal low-frequency and high-frequency components, and to focus the enhancement of the temporal low-frequency component, which may significantly reduce the computational complexity. Specifically, we employ the temporal wavelet transform (TWT) for the temporal frequency analysis, and build a TWT-based multiple-input multiple-output perceptual quality enhancement scheme. First, we use a motion estimation method on the input video to acquire the motion information, and then use TWT to obtain the temporal low- and high-frequency components. Second, we design a deep network to enhance the quality of the temporal low-frequency component. Finally, the temporal high-frequency component and the enhanced temporal low-frequency component are combined by the temporal wavelet inverse transform (TWIT) to generate the enhanced video. Experimental results show that our method achieves comparable perceptual quality to that of the state-of-the-art methods, but reduces the computational complexity to 1/13.