The Communications Research Laboratory(CRL) and the National Space Development Agency of Japan(NASDA) have been studying an advanced satellite broadcasting system that uses 21GHz band. This study has evolved into an Japanese experimental satellite project called COMETS(Communications and Broadcasting Engineering Test Satellite), which will be launched in early 1977. This paper describes an overview of COMETS, concept of 21GHz band satellite broadcasting and the advanced satellite broadcasting mission in the COMETS project.

View full abstract

This paper presents a new region-oriented algorithm for segmentation and motion estimation as an image processing algorithm for improving picture quality of a given input moving image sequence. Usually, a segmentation process is introduced into a motion estimation method to locate motion boundaries, and then motion analysis will be constrained not to combine local estimates across such boundaries. However, the segmentation presents its own problem. The only information on which the segmentation is based is sometimes the image motion estimates themselves. Thus, good quality motion analysis depends on image segmentation, whereas good quality segmentation depends in turn on motion estimation. Therefore, the segmentation problem is extremely difficult to solve separately from the motion estimation problem. To solve the segmentation problem along with the motion estimation problem simultaneously, this paper develops a region-oriented algorithm. The preliminary experiments demonstrate that the region-oriented algorithm works well and is promising.

View full abstract

This paper proposes a new region - oriented coding scheme employing orthogonal transforms. First, a segmentation method based on the k-means clustering algorithm partitions an image into some tens of regions, whose shapes are encoded using the chain-code. Second, some regions where the power of AC components is larger than a constant are redivided into square - blocks and variable - shape - blocks. Then, a mean value and the AC component in each block are encoded by DPCM and OTC, respectively. Simulation results indicate that this coding scheme can overperform the JPEG baseline system. In addition, this paper describes an experimental investigation result concerned with the optimal bit allocation to coding of region - shapes and luminance signals.

View full abstract

Sub-band coding is one of the methods having a high coding efficiency. In sub-band coding, many bits need to be assigned at lower bands where the energy concentrates. Therefore, higher coding efficiency can be obtained by combining sub-band coding with extra/interpolative prediction coding which has a high coding efficiency also at a high bit rate. Moreover, the proposed method selects the optimum variable length codes for every block to adapt to the local character of a picture. It is shown that the proposed method excels the international standard JPEG.

View full abstract

A generic video coding scheme has been studied in IS0/IEC JTC1/SC29/WG11 joint with ITU-T(former CCITT) SGXV/WP1 since June 1991. The video coding scheme is required to have increased functionalities desirable in a broad range of video services. One subject which has drawn interest is "Scalability". In terms of increased function, scalability has the potential to benefit many applications. A key property of scalability is that more than one version of the video signal can be reconstructed from the data representation with the different resolution or visual quality. This paper shows what a scalable video coding scheme is and how the MPEG standard on scalability has been studied and finalized.

View full abstract