We propose that high performance HDTV camera tubes be made by combining new one-inch all-electrostatic electron optics with a High-gain Avalanche Rushing amorphous Photoconductor (HARP). Numerical analysis of electric fields and other experimental data indicated that sensitivity could be increased by making a thicker target, that the dynamic range could be increased by designing the diode gun to have a suitable limiting aperture and that resolution could be increased with a unique new configuration of electron optics. A new tube based on these concepts has a maximum sensitivity 32 times that of standard Saticons. Its amplitude response at 800 TV-lines in the ITE-AR chart is 45% at the picture center and is 40% for the average of the four picture corners. Operation with a large signal-current and a higt signal-to-noise ratio results in the highest picture quality ever attained.

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One of the concepts of lossless universal pattern-matching coding, i. e. coding via copying, is applied to multi-dimensional lossy coding. This application produces an instantaneous-decision coding algorithm based on the concept of coding via copying for low-rate irreversible image compression. Previously proposed instantaneous-decision coding algorithms employ multiple-coding modes, and adaptively choose the proper coding mode for a given input subblock instantly without any delay by using threshold logic based on waveform distortion. This adaptive selection of the coding mode is not optimal because the current selection of the coding mode affects the future behavior of the encoder. To enhance coding-mode selection adaptability, a delayed-decision mechanism known as an (M, L) algorithm is introduced, and a new delayed-decision coding algorithm is developed based on the concept of coding via copying. At low coding rates of less than 0.5 bit/pixel, the delayed-decision mechanism improves coding performance by approximately 2-3 dB, and can compress still images more efficiently than existing discrete cosine transform coding.

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The effects of scanning systems on camera, display, and picture quality characteristics are investigated for the double-rate scanning systems of Hi-Vision. The subject systems are 1125/60/1 : 1 (“Progressive scan”), 1125/120/2 : 1 (“120”), 2250/60/2 : 1 (“2250”), etc. The spatio-temporal frequency responses of a Saticon camera and CRT display are measured, clarifying the influence of the scanning system. The degree of interlace artifacts on each system is estimated from the spatio-temporal spectra of the systems. Finally, subjective tests evaluate subjective impairment by line structure, subjective resolution, and picture quality of the systems. One of result is that the picture quality of current HDTV systems shows further improvement by improving the temporal or spatio-temporal characteristics of systems.

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This paper proposes a high quality halftone method and a highly efficient coding method for halftone images by the method In the proposed halftone method, a M × M threshold-matrix of m × m (m<M) gray tones is adopted as the basic structure of image generation and is suitable for high quality image generation and highly efficient coding For high quality halftone image generation, the matrix is optimized on the basis of the optimal pixel assignment model which has been proposed by us For highly efficient coding of the halftone images, the structure is utilized as a priori knowledge in the coding model of arithmetic coding employed in the proposed coding method Simulation results show that the proposed method is a highly efficient loss less coding method for high quality halftone images

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Color flicker occurs when component signal processing with a field memory is used for a broad-band VCR to output a composite signal with a freeze image This flicker is caused by a residual chrominance signal in the processed luminance signal which interferes with the processed chrominance signal. Two methods are examined to suppress color flicker. One method is to alternately extend or reduce the field period at intervals of two fields when reading out signals from the field memory The other method is to input the luminance signal into a field-noise reducer, and stop writing it into the field memory in a field with an even number of lines. These two methods are employed in a VCR, thereby confirming color-flicker suppression The latter method is applied to an editing function in which the memory-freeze signal and another signal from an external input are mixed, since it can output a standard TV signal.

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