Motion JPEG Decoding via Iterative Thresholding and Motion-Compensated Deflickering

This paper studies the problem of decoding video sequences compressed by Motion JPEG (M-JPEG) at the best possible perceived video quality. We consider decoding of M-JPEG video as signal recovery from incomplete measurements known in compressive sensing. We take all quantized non-zero Discrete Cosine Transform (DCT) coefficients as measurements and the remaining zero coefficients as data that should be recovered. The output video is reconstructed via iterative thresholding algorithm, where Video Block Matching and 4-D filtering (VBM4D) is used as thresholding operator. To reduce non-linearities in the measurements caused by the quantization in JPEG, we propose to apply spatio-temporal pre-filtering before measurements calculation and recovery. Since temporal inconsistencies of the residual coding artifacts lead to strong flickering in recovered video, we also propose to apply motion-compensated deflickering filter as a post-filter. Experimental results show that the proposed approach provides 0.44-0.51 dB average improvement in Peak Signal to Noise Ratio (PSNR), as well as lower flickering level compared to the state-of-the-art method based on Coefficient Graph Laplacians (COGL). We have also conducted a subjective comparison study, indicating that the proposed approach outperforms state-of-the-art methods in terms of subjective video quality.