A personal multimedia-multipoint teleconference system over an N-ISDN, PMTC/N-ISDN, is described. PMTC is a distributed synchronous groupware system that supports desktop multimedia teleconferences and document co-editing services etc., with facial and topic videos, normal audio, and graphics such as character code documents, bit map images handwritten images and a pointer over an N-ISDN. This paper discusses PMTC/N-ISDN's system concepts and its services through the three types of virtual conference spaces, that is, common space, closed space and local space.

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The protection ratios for the conventional FM-Television signals (M/NTSC, MUSE) interfered by the digital broadcasting signals (QPSK) in the 12GHz broadcasting satellite channel was studied. The C/I for just perceptible interference caused by the digital signals were examined with subjective assessments and computer simulations. A non-linear channel equivalent to BS3 transponder were assumed for transmission characteristic. It was confirmed that the protection ratio of co- and adjacent-channel based on WARC-BS was also suitable for QPSK 40Mbps signals.

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We have developed a high quality MUSE-NTSC converter (M-N converter). Two kinds of aliasing distortion are caused when intra-field interpolation is done for the stationary area. In order to reduce the aliasing distortion, inter-frame interpolation and inter-field averaging are performed for the sub-sampled signal which is the converted NTSC signal. As a result, we have removed both of these aliasing distortions using less memory. We also adopt all types of gamma corrections by using digital signal processing. In effect, we have achieved a high quality image which has good linearity and proper color characteristics.

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Now, we have developed the HDTV edit system using UNIHI-VTR. In this system, the scan-converter is used not only as down-converter to copy pictures from UNIHI-VTR to S-VHS VTR but also as up-converter to super-impose NTSC characters on HDTV pictures. And, we have make the best use of existing NTSC standard instruments, e.g. video switcher, character generater and so on. These make it more reasonable e to develop this system.

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NHK has developed a HDTV Standards Converter bidirectional between 1125/60/2:1 and 1250/50/2:1. Notion compensating methods for HDTV standards converter between 60Hz and 50Hz field rate are necessary as well, in order to use the advantages of the increased temporal resolution and to avoid motion judder and motion blur. Inaccurate motion detection and inaccurate motion assignment has to be taken into account in order to avoid additional artifacts. This paper describes the simulations and the hardware design used algorithm of motion compensation which is consider spatial and temporal motion vector flow.

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In coding of SHDI (Super High Definition Images) which consists of appropximate 4000 scanning lines, it is expected that so-called Prediction coding will be effective to maintain their high quality. In this paper, it is shown first that extrapolative and interpolative prediction coding scheme which is effective for HDTV is also useful for SHDI. The optimum quantizer can be performed by using generalized Cauchy distribution which approximates well the probability distribution of prediction error signal of SHDI. Considering the distribution of Prediction error, we propose the following coding scheme:Initially, a prediction error is Selected into two groups, zero value and non-zero value. The information is coded by binary code. Next, a non-zero value interpolative prediction error is coded. The simulation shows high fidelity images whose SNR and bits/pel are more than 50dB and 2 bits/pel have been obtained.

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As the first step of signal compression for 3-Dimensional Hi-Vision system, the method of searching disparity between the right and left images has been studied. Intending to improve the accuracy of matching solution between the distinctive points of the right and left images, the characteristics of the visual system of the human beings have been introduced; the one is the sensitiveness to the contour of the objects and the other is the non-linearity of the sensitivity to the amplitude of the light. The result of the experiments shows that optimized matching method named 'Rubber-matching' is about nine times superior to the conventional block-matching in the accuracy, and about five times superior to the well adjusted variable-block-size-matching.

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In binocular stereoscopic images. Puppet Theater Effect has been pointed out to be a distortion of size. About this probrem, we made subjective evaluation tests varying pick-up conditions such as the distance between LR cameras, pick-up distance and focal length of a lens. We chose a lady standing on a corridor as an evaluation subject. As a result, these evaluation tests showed a tendency to feel the lady more tiny and small in stereoscopic images, in comparison with in two dimensional images. And the tendency was more remarkable in case of enlarging the distance between LR cameras and short pick-up distance.

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We have reported the algorithm of hidden surface removal and diffuse reflection shading process for electro-holographic display. Shadow algorithms are suggested for two dimensional display. We propose a method to adapt this algorithm to computer generated Fresnel hologram. Our display system has horizontal parallax. So, we propose a method in continuous viewpoint. The experimental results are also discussed.

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One way to reduce the holographic information is to record the hologram on only array of small areas uniformly distributed over the holographic plate. When looking at such a hologram, we were looking through a screen. To eliminate this effect, the recorded hologram is duplicated in the adjacent blank areas. But this method causes a blurring of the reconstructed image. Then, in this paper, the hologram divided into small blocks is transformed the frequency division, and we interpolate the frequency component into the blank area. In this method, we can eliminate the screen effect and the blurring of the reconstructed image.

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