Kazuo Sugimoto

Inter frame coding with template matching spatio-temporal prediction

A new algorithm is proposed for predicting pixels for inter frame coding without side information. There are many approaches in the past that exploited either spatial or temporal correlations for generating prediction signals of an image in a block-by-block basis. Our method proposed in this paper exploits both spatial and temporal correlations at once to predict the pixels to be encoded. The prediction is achieved by using a template matching mechanism, with reference to previously reconstructed groups of pixels in the same frame or adjacent frames, to fill in the pixels of target regions of a frame. This process is conducted at both the encoder and decoder, and hence allows the decoder to produce the same predictor as the encoder does without any side information. Our coder uses the proposed prediction in addition to conventional motion compensation means. Simulation results show that our approach achieves up to 11.14% of improvements at the same PSNR over a codec which uses conventional block-based motion compensation.

Hierarchical mode search with classification of bisectional prediction modes based on the position of motion boundary [video coding]

Video coding schemes, equipped with various kinds of prediction modes, improve coding efficiency by offering efficient prediction modes that adapt to the motion in a macroblock (MB). Operation time for motion estimation and mode selection, on the other hand, increases with the number of prediction modes. We have proposed a motion compensated prediction method (arbitrary-shape partitioning motion compensation: APMC) equipped with various inter prediction modes which adapts to the motion boundary of objects on an MB basis. This paper confirms the coding efficiency of APMC in comparison to the final specification of H.264/AVC and introduces a method to improve the computational performance of APMC by using a hierarchical mode search method based on motion boundary position within MBs. Simulation results show that APMC improves coding efficiency by about 5% in comparison with the final specification of H.264/AVC, and the proposed hierarchical mode search method decreases the operation time to about 60%, while maintaining the coding efficiency.

Bidimensional dictionary and coding scheme for a very low bitrate matching pursuit video coder

In this paper we present a video coder based on a redundant dictionary that employs nonseparable bidimensional functions. The algorithm used for the representation of the residual of motion estimation is matching pursuit (MP). The proposed dictionary has new features capable of catching curved and oriented contours typical of the residual of motion estimation in natural video sequences. An adaptive grid approach is adopted for the coding of atoms and this is combined with an innovative coding method employing an arithmetic encoder. The proposed coder shows improvements over H.264 in terms of compression efficiency, with up to 20% gains for very low bitrates.

A video coder for low bitrate mobile video streaming

Achieving very low bitrates for video applications in a mobile environment is essential. Video codecs standards evolution had a tremendous impact in the development of digital video, making possible today widespread usage of video data. At the same time it had an impact on the direction of research, biasing most of the efforts towards block based video. Alternative approaches may though lead towards different architectures able to provide higher compression efficiency. In this paper we propose a Matching Pursuit (MP) based video coder that adopts a generalized sub-pixel motion compensation and arithmetic coding. We introduce a new dictionary, and an adaptive grid for atom coding combined with an arithmetic coder. Comparison with H.264 show an improvement of up to 20% in compression efficiency for the same PSNR

Generalized motion compensation and arithmetic coding for matching pursuit coder

Matching pursuit (MP) based video coder represents an active alternative to conventional block based DCT based architectures R Neff et al. (1997). In this paper we propose a generalized motion compensation method and an entropy coding method for MP based coder. Motion vectors are combined with the cut-off frequency level of loop filters applied to the reference frame. Exploiting the characteristics of MP atoms, the latter are efficiently coded by employing an adaptive grid size combined with context based adaptive arithmetic coder. Reordering of atoms in each grid is also applied. Simulation results show that our proposed method outperforms traditional fixed grid based approach.