Mitsuho Yamada

Definition of gazing point for picture analysis and its applications

The authors have been analyzing images by eye movement. For this purpose, it is necessary to decompose the eye movement into a component to accept information from a gazed object and a component to shift the gazing point. The point considered in the foregoing is called the gazing point, which is defined in this paper based on the property of the pursuit eye movement. Eye movement velocity of 5 deg/s is used as the threshold to separate the two components. As a result, it is made possible to separate clearly the eye movement into the gazing point component and the shift between the gazing point. A vision analyzer based on this definition of the gazing point was developed, which can analyze comprehensively the eye movement in real-time. As an example of the application of the vision analyzer, the difference of the eye movement in watching the VDT image and the usual dynamic picture is analyzed. Furthermore, as an application to the analysis of art, an experiment was made as a reference material for the analysis of Sharakus ukiyo-e painting. The results of experiments are described, indicating that the definition of the gazing point is adequate.

Combination enlargement method of viewing zone for computer-generated holography

We have developed a new system based on computer-generated holography using a hologram plane with a sampling structure like a liquid crystal display. This system can eliminate beams from conjugate images and enlarge the viewing zone, which are achieved by combining the following two methods. The first method enlarges the viewing zone by using higher- order diffraction beams generated because of the sampling structure of the hologram plane. If the angle between the object beam and the reference beam is larger than the angle determined by the sampling period on the hologram plane, aliasing occurs in the fringe patterns. In this method, the viewing zone is enlarged by using a spatial filter to extract the object beams from the higher-order diffraction beams generated from aliasing and then combining them. The second method is a modification of the single-sideband method that is known to eliminate the conjugate beams and to restrict the viewing zone to a narrow range. The modified method improves this restriction by dividing the range of the object beams and reproducing each of them. This paper presents the developed system, and the results of experiments that confirmed the effectiveness of this system in enlarging the viewing zone.

Relation between visual effects and gain of motion parallax

This paper examines visual effects of motion parallax (MP) which is an important element of depth perception. A display technology was developed which does not cause a delay of motion parallax to a viewer watching an image with a motion parallax related to viewpoint position. Using this apparatus, a method of control was examined which affects a viewers emotion by changing the magnitude of the motion parallax. A term “gain of motion parallax Gm” which represents the magnitude of a motion parallax is defined. An assumption is made that a visual effect induced by an image with a motion parallax depends on Gm. To prove this assumption, the undetectable threshold of a delay of a motion parallax was found to be approximately 60 ms. It was confirmed that the motion-parallax display apparatus developed has shorter delay than this value. By changing the value of Gm, subjective evaluations were carried out for three evaluation items: “sensation of depth,” “reality” and “linkage.” The results show that these three items form functions of Gm which are “saturation shape,” “dull peak shape” and “sharp peak shape,” respectively.

Integral three-dimensional video system

A three-dimensional video system based on integral photography using a micro-lens array is described. Four problems with the system and technical means to solve them are proposed. Especially, resolution characteristics including those of pickup and display are described in detail. The experimental system using television camera and liquid crystal display (LCD) provides full color and autostereoscopic 3-D images with full parallax in real time.

Binocular fixation-point shifts induced by a limb occlusion

We analyzed binocular eye movements to investigate how human see a limb when limb-occlusion occurs. The results suggest that human tend to shift each eyes fixation-point outward when they perceive limb-occlusion. Limb-occlusion has a greater effect for the fixation-point shifts than the depth discontinuity due to differences of visual distance.

Dependence on the display methods of change in accommodation and convergence when a target moves along the depth direction

We have studied human behavior while using a small tablet or a digital book in terms of eye movement. These display media are widely used in conditions that cause hand movement, like on a moving bus or train. Therefore, we focused on the tracking accuracy of accommodation and convergence while subjects viewed a display that was moving in the depth direction. We developed an experimental device that measures the lens accommodation and convergence eye movement simultaneously and can be combined with equipment that moves a small tablet or a digital book linearly in the depth direction. We then evaluated changes in accommodation and convergence angle during depth-direction movement with different kinds of display media, fonts and font sizes. The amount of change in accommodation showed a tendency to depend on the display medium and the size of the font, and the type of font to the motion of a depth direction. The change in the angle of convergence was not dependent on the type of display medium, and the size of the font and the type of font depended only on the depth movement of the target. The tendency overshot in the direction approaching a subject was seen.

Measurement and analysis of human brain function through head and eye movement

This paper describes the measurement system of head and eye movement for analyzing brain function. This system is able to measure the movement of the gaze in space in real time by converting the degree of head movement to that of eye movement. It superimposes this calculation result onto the image seen by the subject. For analysis of brain function, such us a comparative study of the gaze movements of Alzheimers disease patients and healthy people, this system provides two methods. One is for movement data of the head and eyes while the subject is tracking changes in targets, and the other is for minute eye movement data while the subject stares at a fixed point.

Analysis of lines of sight while playing sport using a newly developed lines-of-sight analyzer

The Olympics will be held in Tokyo in 2020, and the training of the athlete using technology has been gaining attention. In an effort to refine the competitive ability of top athletes by evaluating their performance objectively, we have focused on eye movement and head movement. Since the field of view moves according to the athletes head movement, which is a problem for the conventional method of measuring eye movement, we proposed a new method of analysis of lines of sight which can record head movement during a competition and make it easier to analyze by superimposing the lines of sight on an externally recorded fixed image. With the goal of measuring the lines of sight of an athlete during an actual competition, we made a video during a competition and had an athlete observe the video in a laboratory. First we compared the video in which only the eye movement was measured and the field-of-view image moved according to the head movement with another video in which the head movement and eye movement were measured and the image did not move in spite of the occurrence of head movement. The results of the experiment, which involved baseball as the competitive sport, showed the effectiveness of our proposed system. Furthermore, we showed the difference between the lines of sight of an experienced and an inexperienced catcher, and the difference in the lines of sight of a first-base runner between a left-handed pitcher and a right-handed pitcher.

Objective evaluation of the feeling of depth in 2-D or 3-D images using the convergence angle of the eyes

Measurement of the convergence angle of a viewers eye can be useful in evaluating his perception of depth while watching, for example, HDTV or 3D stereoscopic pictures. First, the target was moved away from the subject to determine convergence characteristics in a natural scene. The convergence angle changed as the target moved and the distance calculated using the intersection of the sight lines of both eyes also corresponded well to the actual position of the target. Secondly polarized binocular stereoscopic pictures were used. The Parallax of the CG pattern changed at 5-second intervals toward the foreground or background in steps, from 0 to one of three parallax amplitudes. As a result, the convergence distribution widened as the parallax increased. This spread was large when the target was presented in the foreground. Next, a program prepared stereoscopically was presented in 3D with parallax and in 2D without parallax. The results indicated that the convergence varied even when viewed 2D and that the convergence distribution was larger in 3D than in 2D. As for the possible cause of this change with 2D picture, the influence of the feeling of depth produced by the 2D picture should be considered.

How Effective is Using Lip Movement for Japanese Utterance Training

A R T I C L E I N F O A B S T R A C T Article history: Received: 20 December, 2016 Accepted: 20 January, 2017 Online: 28 January, 2017 Lip movements have long been the subject of research. There are many methods of lip movement recognition, such as the calculation of the amount of movement compared to a matching face pattern. In a previous study, we investigated utterance recognition based on the power spectrum by focusing on lip movements, which is one aspect of multimodal voice recognition systems. However, we found that the utterance recognition rate varied depending on the participants throughout our research. For this reason, we propose a training method for the purpose of utterance improvement in Japanese.