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Shota Hino, Kishore Sriadibhatla & Jingyang Xue Stanford University EE 398A Final Project. Direction-Adaptive Transform of Motion-Compensated Residuals in Video Sequences. Overview. Motivation Directional Adaptive Transforms for Residuals Motion compensated residual computation
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Shota Hino, Kishore Sriadibhatla & Jingyang Xue Stanford University EE 398A Final Project Direction-Adaptive Transform of Motion-Compensated Residuals in Video Sequences
Overview • Motivation • Directional Adaptive Transforms for Residuals • Motion compensated residual computation • Residual clustering • Training KLT on each cluster • Results & Performance Comparison • Coding Gain vs. Directions • Rate-Distortion comparison with standard transforms • Conclusion • Questions
Motivation • Direction adaptive transform achieves better coding performance for still images • Same is true for residual images? • Maximum coding gain using KLT?
Motion Compensated Residual Images • Motion compensated residuals for six different quantization levels • Block matching based on MSE and motion vector • Search range of [-16,16]
Block Based Residual Clustering • Clustering using dominant direction in 8x8 block • Histogram of gradients, find dominant angle based on sum of magnitude threshold • 9 groups: -67.5 to 90 deg @ 22.5 interval + No direction • Input source can be residual or predicted signals 45 deg in prediction picture Original Image Residual Image
Trained KLT on Cluster Basis Function for direction -67.5 KLT Covariance Matrix
Mode Control Encoder XOR Decoder MC Hybrid Coder with KLT Clustering & KLT Selection Intraframe KLT coder Intraframe KLT Decoder Motion compensated predictor
Coding Gain Coding Gain = • Coding gain of DA-KLT compared with 3 other standard transforms. • -- DCT • -- KLT trained on whole image • -- DAPBT
Coding Gain Comparison, Train = Test Prediction Signal Based Clustering Coding Gain Train: Stefan.cif Test: Stefan.cif
Coding Gain Comparison, Train = Test Residual Based Clustering Coding Gain Train: Stefan.cif Test: Stefan.cif 10
Coding Gain Comparison, Train = Test Prediction Based Clustering, train on 5 video clips Train: Flower.cif, Highway.cif, Stefan.cif, Tempete.cif, Highway.cif Test: Flower.cif, Highway.cif, Stefan.cif, Tempete.cif, Highway.cif 11
Coding Gain Comparison, Train != Test Prediction Based Clustering, train on 5 video clips Train: Flower.cif, Highway.cif, Stefan.cif, Tempete.cif, Highway.cif Test: Coastguard.cif 12
DA-KLT vs other Transforms • Uniform Quantization - 6 levels • Trained & Tested on 40 frames of Stefan • Direction 6, prediction signal based Prediction Signal Based Clustering
DA-KLT vs DCT Direction 6 - Zoom Prediction Signal Based Clustering
DA-KLT vs DCT Direction 8 Prediction Signal Based Clustering
DA-KLT vs DCT Direction 8 - Zoom Prediction Signal Based Clustering
DA-KLT vs DCT Direction 6 Residual Based Clustering
DA-KLT vs DCT Direction 6 - Zoom Residual Based Clustering
DA-KLT vs DCT Direction 8 Residual Based Clustering
DA-KLT vs DCT Direction 8 - Zoom Residual Based Clustering
Frame Comparison Original Image DA-KLT reconstructed
Frame Comparison - Detail DCT Reconstructed DA-KLT Reconstructed Original q_step = 16
Frame Comparison - Detail DCT Reconstructed DA-KLT Reconstructed Original q_step = 16
Conclusion & Future Directions • Directional Adaptive Transforms can outperform DCT and DA-PBT if train KLT for specific video source • Can achieve 0.1 to 0.4 db at high rate in ideal case • Prediction based clustering more practical at the expense of less accuracy • Currently seeing slightly worse coding gain performance using “universal” KLT on other video sources • Future Directions • Explore different quantization scheme for KLT • Better clustering algorithm based on prediction signal • Searching for better universal KLT or separable transforms 24
Thank you • Questions? 25
Coding Gain Comparison, Train = Test Residual Based Clustering, train on 5 video clips Train: Flower.cif, Highway.cif, Stefan.cif, Tempete.cif, Highway.cif Test: Coastguard.cif 27
Coding Gain Comparison, Train != Test Residual Based Clustering, train on 5 video clips Train: Flower.cif, Highway.cif, Stefan.cif, Tempete.cif, Highway.cif Test: Coastguard.cif 28
DA-KLT vs DCT Direction 1 Prediction Signal Based Clustering