This paper describes and experimental study of a new coding method for face to face video communication using small screen. A new coding method that uses synthetic complement and emphasis accordant with edge pattern is proposed.

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The Adaptive Block Truncation Coding (ABTC) is a high efficient coding scheme for still pictures. In this paper, the relationship between ABTC encoding parameters and quality and coding bit-rate of its reconstructed images are described. In this coding scheme, each value of five parameters must be decided in encoding process in order to encode individual image with high efficiency. This operation complicats operators in practical use, so an automatic decision method for ABTC parameters are examined and its effects are also described.

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Hand movement in hand-held image reader operation is studied through mockup experiments involving hand-scanning speed and vertical movement, i. e., straightness in relation to the figures being read. Results are shown for hand-scanning speeds from 10 mm/sec to 300 mm/sec, and 2-4 mm movement variations measured, perpendicuraly away from a chracter line. It is found that a suitable reading location is at 2-4mm from the left side of the scanner. This allows users to understand more clear what is being read. A hand-held image reader with good operation characteristics is designed based on these results, and a low distortion image is obtained.

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Conventionally, performance of Image Coder is evaluated by SNR of reconstructed pictures. However, SNR is not a good criterion. For instance, blocking artifacts are more perceptible than a random noise and deteriorate picture quality. In this paper, we propose a new measure of picture quality considering not only a random noise but also a correlated noise, Five deterioration factors are considered ; fl : weighted mean square error (WMSE), f2 : WMSE lager than visual threshold, f3 : changes of errors between successive pixels at the block boundaries, f4 : autocorrelation of errors, f5 : measure of errors around the contours. Careful assessment tests are carried out and a new measure is obtained by utilizing multiple regression analysis and principal component analysis. The individual principal component obtained by principal component analysis represents characteristics of error clearly, and the dependence of measure on the type of image is greatly improved. Simulation results show that this measure well approximate the Mean Opinion Scores.

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In this paper I discuss a portable telephone system design which is aimed to realization of the ultimate communication which means one can telephone at any time, any place, and to any place. The major problems to realize the system are : moderate frequency spectrum, service cost, privacy, the pertinent access method to the portable telephone of which location moves with person travel, radio zone costruction, compatibility with present various mobile systems, and hardware techniques. This paper will give some solution for the above problems. The necessary frequency spectrum would not be so much as we expected because the calculation result indicates only 3〜5 MHz will be required.

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