[in Japanese]

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[in Japanese]

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A “weighting function” is defined for evaluating monochrome still-picture quality in the spatial frequency domain. The weighting values of the function can be determined from the relationship between the MOS (Mean Opinion Score) and the spatial-frequency-selective noise level. A hundred and six weighting values are calculated in the spatial frequency dommain of 256 (TV lines) x 256 (TV lines). When the ratio of viewing distance to picture height is 7, the weighting value at 3 (cpd, cycle per degree) shows maximum value. The function is isotropic in the region from 3 (cpd) to 8 (cpd) and anisotropic at over 10 (cpd).
Using the weighting function, a new objective measure named WSNR (Weighted Signal-to-Noise Ratio) is also defined and applied to pictures degraded artificially. The picture quality is degraded by adding random noise, by passing through a two-dimensional low-pass filter, or by distorting blocks. Experiments using different portrait pictures show good correlation coefficients between the MOS and the WSNR, 0.93-0.97.

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This paper describes a picture-coding technology for a digital still camera which records still images on a memory card The JPEG (Joint Photographic Experts Group) is working on standardizing the digital compression and coding of still images. It is desirable to apply this standard to the digital still camera However, the number of bits to record a fixed number of images on a memory card is comparatively small We propose a method of controlling the bit rate by calculating the activity of images before coding The quantize matrix and the bit allocation for each coding block are determined by the image and the block activity As a result, the number of images recordable on a memory card is fixed and the coded data can be decoded with a standard JPEG decoder

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In this paper, slight near accommodation associated with vertical eye movement is measured dynamically for the first time with the aid of a newly developed three-dimensional optometer III. The amount of accommodation decreases when the target position is moved towards the subject. The results agree with P. H. Ripple's results (1952) on the accommodation induced at far points, but contradict with the accommodation evoked at near points. The results also differ on the accommodation evoked by horizontal eye movement. A plausible explanation is presented by comparing the response of the pupil diameter with the accommodation response.

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Hi-Vision pictures have been reproduced experimentally on a 33-inch-a dc gas-discharge color panel with 1024 x 800 cells of 0.65 mm pitch. The panel uses a pulse memory-drive scheme as the first step towards making a Hi-Vision flat-panel display. About 40 percent of the area of an original Hi-Vision picture with the standard 1125 lines/60 fields was displayed because of the limited number of panel cells. The memory operation over the whole effective area of the panel was stable for the two-line-at-a-time access drive, due to the introduction of a two-step sustain pulse and improved fabrication techniques. Signal processing circuits developed for the pulse memory panel allowed fairly high-quality pictures to be reproduced on the panel.

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The effects of both continuous Gaussian noise and burst Gaussian noise on TV picture degradation are studied using a Gaussian noise generator that allows control of noise parameters such as power, ACR, duration, and occurrence frequency. The disturbance is subjectively evaluated. The amount of TV picture degradation is the same for both noises was. However, when the noise power is constant, the mean opinion scores for the burst noise at a constant burst duration approach those for the continuous noise as the occurrence frequency increases.

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High-efficiency picture signal coding and high-density digital recording are important technical subjects for the next generation of digital VTR.
This paper proposes a new tracking control system for narrow-track digital recording.
We have developed a wideband dynamic tracking system using a voice-coil-type magnetic actuator to move the magnetic head and an observer based on modern control theory to suppress the mechanical resonance.
We have improved the stability of the tracking servo system so that it can fully track a recorded pattern with a 6, μm track pitch from the initial cross track condition.
We have also developed a method for generating the tracking error signal by using 12-15 modulation code with a built-in pilot signal.
When combined with a phase-sensing, this method accurately detects track linearity for digital recording.
We also confirmed the improvement of the tracking stability and accuracy when repetitive control is applied to the developed tracking system.

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This paper describes an experimental hardware implementation of an STM-1-rate (155.52 Mb/s) CBR-mode HDTV CODEC for ATM transmission in B-ISDN. This CODEC has a data-compression part with a block-adaptive DCT algorithm and has an ATM transmission interface with cell loss compensation using layered-coding and interleaving. Three types of gate-array LSIs are also devoloped for compact desktop-size hardware.
Experimental transmission using an ATM switch confirms that the CODEC achieves picture quality sufficient for secondary distribution in the ATM environment of Broadband-ISDN

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[in Japanese]

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[in Japanese]

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[in Japanese]

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