[in Japanese]

View full abstract

We are developing a noise reduction scheme as a pre-processing filter for the HDTV video CODEC. HDTV noise comes mainly from the contour emphasis process of the HDTV camera, which deteriorates the compression efficiency of interframe coding. Conventional simple interframe noise reduction often generates motion blur distortion.
In this paper we propose a noise reduction scheme with less motion blur distortion which is controlled by the interframe signals expanded spatially and temporally. We show that our scheme produces inproved picture quality and coding efficiency.

View full abstract

The purpose of this study is to objectively and quantitatively estimate mental fatigue through analysis of pupillary light response with minimum constraint on subjects. Three experiments were performed as follows. First, the effect of retinal dark adaptation on the pupillary dynamics was analyzed. Secondly, pupillary light response and CFF were measured during a two-hour addition task. Thirdly, the relation between mental fatigue and visual organs was investigated. Results were as follows : (i) The magnitude of constriction changes with the retinal adaptation, while, other dynamic characteristics do not. (ii) Mental fatigue caused by the addition task decreases the constriction and dilatation velocities of the pupil. (iii) The changes in the pupillary dynamics in this study can be explained as an elevated state of the parasympathetic nervous system caused by mental workload.

View full abstract

A novel method to evaluate the quality of pictures is presented. In image pickup systems, including human vision, shot noise is inevitably added to the observed image during the photo-electric conversion process. To quantitatively express the influence of shot noise on the image signal, we propose a new measure of “detectability” of the pattern, based on Iijima's picture observation theory : a logarythmic function of the ratio of the NORM of the pattern to the fluctuation. This detectability reveals that the accuracy limit of blur detection corresponds to the residual focusing error in human visual systems. Also, the measure shows characteristics similar to sharpness, except for extremely short viewing distances.

View full abstract

An algorithm for tracking the position of a moving object in a naturally moving image is proposed. In this algorithm, the first step is to simply identify the objcct. Then, the object is segmented from the back ground image by the local histogram growing method. The histograms in the perceptual color system (hue, saturation, brightness) are insensitive to video-camera movement and rotation, as well as deformation, shrinkage, and enlargement of the object. Last, the position of the object is detected by the optimal histogram matching method. Real-time experiments have verified the effectiveness of this technique.

View full abstract

An image sensor for image processing has been developed. A 1/4-inch 250, 000 pixel amplified MOS imager has been equipped with three independent outputs. The amplified MOS imagers nondestructive read-out operation and three lines of memory built in the sensor make it possible to output the signals of three independent lines simultaneously. By applying this function, a vertical DTL circuit and an FPN suppression of 10.8 dB are realized without an external memory.

View full abstract

[in Japanese]

View full abstract