[in Japanese]

View full abstract

Pyramidal region segmentation can be used to classify the regions of an image into two categories : the regions “not having to preserve the waveform of image” are encoded only with fractal parameters, and the regions “having to preserve the waveform of image” are encoded using any waveform coding method [DCT, VQ, etc.]. And those blocks containing region contour lines can be classified into two categories according to the complexity of the shape of contour lines : the blocks with simple contours can be encoded using the same method used for encoding the regions “not having to preserve the waveform of image”, and the blocks with complex contours can be encoded using waveform and fractal coding methods. Our experiments this combination of coding methods made it possible to encode an image at 0.4-0.7 bits/ pixel.

View full abstract

A folded dipole antenna placed in front of a reflecting screen is usually used as the wideband radiator of curtain antennas for HF broadcasting, and the bandwidth radiated has been increased by using a multiple-wire structure for the dipole. This paper uses the moment method analysis to evaluate some characteristics of the antenna elements, such as their frequency and mutual coupling. Calculating and comparing the bandwidths of six antennas with multiple-wire dipoles confirms that this structure increases the bandwidth of the dipole. This paper also describes how the calculated mutual coupling of two-pair folded dipoles placed in both sides of the screen depends on the screen parameters, and it describes the relationship between antenna structure and the radiation pattern.

View full abstract

HDTV programs are presently being made according to the 1125/60/2 : 1 standard and the 1250/50/2 : 1 standard. Cooperation between the producers using different systems requires that standards converters be used, and such converters with motion compensation to reduce the generation of unnatural movement in the converted pictures are starting to be introduced. We have developed an experimental motion-compensated HDTV standards converter that can the two types of HDTV signals in real time. To improve the quality of the converted picture, we have developed better ways to detect the motion vectors by the iterative gradient method and assign these detected vectors. We have found that this improved conversion method results in picture quality that is acceptable for broadcasting general programs. This paper reports primarily on the motion detection and the field rate conversion.

View full abstract