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Human observers are able to allocate visual attention to multiple locations in a dynamic environment simultaneously. However, this ability depends on an individuals’ capacity to monitor the tracked objects' number, size, speed, and distance between objects. Moving objects in the real-world require that we independently allocate attentional resources to them. Recent studies have demonstrated that observers can focus attention on one location and ignore other locations; tracking performance improves when moving objects are rendered on a range of depth planes, and observers cannot track a moving object that abruptly changes depth in a 3D environment. We investigated whether an object’s abrupt or gradual changes improved attentive tracking under stereoscopic viewing in two experiments. These experiments indicated a similar pattern regardless of the depth-changing characteristics of the objects. Results demonstrated that abrupt- or gradual-changes of moving objects under stereoscopic viewing do not increase a tracking task's difficulty.

We investigate a tool to aid the viewing of PC displays by Unilateral Spatial Neglect (USN) observers by preventing overlook of the left side of the focused window. The basic concept of this tool is using observer's requests to magnify an appropriate part of the display. Based on user-interface trials, three techniques are employed: (1) whole window flashing when opening the magnifying window to realize effective attention, (2) temporal control sequence uses same special key (Ctrl, Alt, etc.) followed by normal key for easy operation by hemiplegia users, and (3) a color combination design to emphasize four sides of the focused window frame to ensure attention is paid to the left side. This tool is also effective for users with presbyopia and/or users who want to add more active window effects for presentations.

HUD is a key cutting edge technology for automobile display systems and is expected to become increasingly popular in the near future. Before starting mass-production, we should carefully consider (1) effects of user diversity (e.g., skill, age, and color vision deficiency, etc.) and (2) effects of HUD on the human visual system (e.g., high dynamic range of background illumination, stereopsis conflict created between background still and/or moving information (actual) and moving information with driver (artificial), and human-vision characteristics of resource distribution for different direction motions, etc.). In this paper, we first describe (1) a primitive analysis of the effects of HUD on the human visual system from the aspects of background illumination and color vision deficiency and (2) a summary of our previous work on the visibility of moving information. Our key finding is the necessity of a diffuser and an attenuation filter for separating real background information from the artificial information.

Visibility of flat and curved simulated displays with 8K resolution are compared. Experiments show that (1) curved displays are preferred over flat ones, however, (2) curved displays with high resolutions might induce strong shape-aftereffects, even if the curvature is small. This suggests visual effects of geometrical distortions in curved displays should be examined further.

Results of earlier multiple object tracking (MOT) studies imply that humans can track several moving targets in a 2D environment simultaneously. Recently, a study suggested that stereoscopic depth has positive effect on tracking multiple objects when the objects are presented separately on multiple planes. However, it remains unclear whether or not humans can track moving targets in a real 3D environment. In this study, we investigated this issue displaying four targets and four distractors on near and/or far depth planes separated physically by 6, 10 or 50cm using a half-mirror and two CRT-monitors. In addition we also tested whether participants could track the targets when either a target or a distractor changed depth during tracking. Our results suggested that performance dropped if the targets were presented on both depth planes especially when the distance between the planes was 50cm. In addition, participants could track a depth-changed target if targets were presented on both planes before the start of a motion phase regardless of whether the initial state of targets distribution randomly varied or not, whereas they failed to track the target if all targets were presented on a single plane before MOT. In conclusion, humans have the ability to set attention on a wide range for MOT in a real 3D environment, with the provision that the efficiency of the tracking is critically dependent not only on the distance in depth but also on an initial state of distribution of the targets without the predictability of the initial state.

Some stereoblind observers do not perceive depth of 3D stimuli that depends on binocular disparity. These individuals, who have no disabilities, comprise over 5% of the general population. In addition, 17–30% of nonstereoblind young and young–middle people do not use disparity information in certain 3D environments, a phenomenon known as pseudo-stereoblindness. This study aimed to investigate the relationship between aging and the proportion of pseudo-stereoblindness in the general population. In an experiment, 134 nonstereoblind participants, ranging in age from 17 to 83 years, judged subjective depth of 3D stimuli containing binocular disparity and pictorial depth cues. Results showed that the proportion of pseudo-stereoblindness among young (17–24 years old) and young–middle aged observers (25–39 years old) was 29%, in both cases. However, the proportion of pseudo-stereoblind observers increased in older populations: 65% and 82% in the middle (40–54 years old) and senior (55–83 years old) age groups, respectively. These results suggest that a number of people, especially in elderly populations, have trouble perceiving depth from binocular disparity in 3D graphic contents despite their essential ability to use disparity information.

We propose a hue-blending method with improved red-green color segregation capability that supports dichromacy. Subjective test results suggest that the proposed method yields quite high red-green color segregation performance. Furthermore, matches or exceeds the performance of previous methods as regards understanding color perception offered by trichromatic views.

We found that 30 % of non-stereoanomalous observers, aged 19 to 25 years old, did not use disparity in making depth judgments in 3D-graphic environments. However, several questionnaires indicate that the use of disparity can be learned unconsciously, suggesting that poor stereopsis can be improved by appropriate training procedures.

We propose a real-time color simulator employing (1) 90-degree-hue-rotation method (supports red-green opponent color perception for dichromacy) and (2) simple red-green hue reduction method (enables red-green color deficiency). Subjective test results suggest that the proposed simulator will greatly help mutual understanding of color perception.

We show that the recognition rate of scrolled characters is decreased/increased when character-scrolling direction is congruent/incongruent with body-yawing direction compared to the rates in the body-stationary condition. Similar eye movement patterns are observed regardless of the character recognition rate for most subjects. These results suggest that attention, i.e., distribution of brain resources for visual processing, is modulated by the relationship between stimulus-motion and body-rotation directions.

An automatic vehicle speed measurement system is presented that can reliably associate the vehicle ID with the retrieved vehicle speed. The system captures images of vehicles passing between two points on the ground that are in the same vicinity, using a pair of linescan cameras installed in a parallel configuration, and measures the speed of passing vehicles by measuring the time taken for the vehicle license plate to move between the two points. In the proposed method, a pair of linescan cameras arranged in parallel is first used to detect passing vehicles and retrieve images of the front sections of the vehicles by capturing images of the vehicles from an angle diagonal to the direction of motion. High-resolution images of the front section of the vehicles are obtained by image capture at a diagonal to the direction of the vehicles in order to obtain high spatial and temporal resolution images of the objects passing in front of the linescan cameras without the images being overly large. However, the license plate in the retrieved images is distorted depending on the position of the plate and the vehicle speed, and this distortion is corrected by performing a geometrical transformation on the images, based on the position at which the license plate passes the cameras and the time the vehicle takes to pass, as determined by finding corresponding blocks. After this, license plate recognition is used to determine the vehicle speed at the position of the license plate. A 24-hour vehicle speed measurement experiment that used an infrared LED for illumination only during the nighttime achieved an 85.1% success rate in measuring the speeds of vehicles at the position of the license plates, thus verifying the validity of the proposed method. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 89(10): 33–45, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20274

For effective guidance of walking, the authors developed a quantitative method for evaluating the quality of walking based on physical feature parameters reflecting the views of specialists in walking guidance. The concept of “quality of walking” comprises foot movement, balance, including the upper body, and the aesthetic aspect. This study focuses on foot movement, which allows easy relation of subjective evaluation and physical features. Specifically, two physical features were investigated, which are considered the important requirements in assuring balance in foot movement. They are (1) supination of the sole (after the heel strike, the center of gravity passes slightly outside the body) and (2) rolling (the sole is used successively from heel to toe). The track of the sole pressure point was measured with a pressure sensor, and the difference between the instructor and the learner was represented by spatial and temporal feature parameters. The multiple regression equations for the two feature parameters and the comprehensive evaluation by visual inspection by the instructor were compared. It was found that these feature parameters are useful as evaluation parameters for the quality of walking (with a contribution ratio of approximately 50%). An experimental evaluation device for walking with the data visualization tool was constructed, which implements the estimation function for the quality of walking. It is found that the device can be helpful in the actual guidance of walking. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 89(4): 42–54, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20237

An apparent 3-D image can be perceived from only two 2-D images displayed at different depths, when an observer views them from the direction in which they are overlapped. The two 2-D images are created from an original 2-D image by dividing its luminance according to independently obtained depth information. Subjective test results show that (1) an apparent 3-D image is perceived and (2) the perceived depth continuously varies according to the change in luminance ratio between the two 2-D images.

A method to analyze gait based on the foot pressure distribution for several steps performed in a natural state would be useful for analyzing gait attributes and walking motion. Extracting each foot region from the foot pressure distribution is a problem in this situation. In this paper, the authors propose a method to measure the position of the foot region by focusing on distinguishing between when the center path of the foot pressure distribution when walking approximates a sine wave or follows a straight line with respect to the walking direction, and to automatically extract the foot region based on grouping the regions around the estimated positions. Based on the results of evaluation experiments, fast, accurate extractions were confirmed for various gait patterns used when analyzing gaits in rehabilitation therapy. The extraction rate was 100% for natural gait in healthy people, and about 98% overall for people with gait impairment. This rate required roughly 1 second of processing. In addition, for gait with shoes, the extraction rate was 100% for natural gait, and 90% when subjects were walking irregularly. This shows that the authors' method can also be applied to the field of crowd dynamics if one person is walking alone, as when giving gait guidance to a healthy person. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(10): 15–26, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20104

This paper describes a method that uses video imaging and foot pressure distribution to estimate a person's lower body posture when walking. The method first estimates the position, posture, and size of the subject, from his or her foot pressure distribution.These estimates are represented by stick models, which are then projected onto video images to estimate the skeletal position. This method was tested on 90 walking patterns of 9 women, and the results show that most of the estimated skeletal structure lies inside the leg, thus confirming that this method functions effectively by repositioning the structure to the center of the leg and matching it to the edge of the video image.

We have found a novel three-dimensional (3-D) display mechanism using only two 2-D images displayed at different depths. It is based on a new perceptual phenomenon induced by the human binocular visual system and enables an observer using no extra equipment to perceive an apparent 3-D image of continous depth when the luminance is divided between the 2-D images according to the 3-D image depth. We have also develop a prototype direct-vision 3-D display using this mechanism. It can easily produce moving 3-D color images by using color conventional 2-D displays.

This paper introduces a method that can generate continuous human walking motion automatically on an arbitrary path in a three-dimensional (3D) modelled scene. The method is based on a physical approach that solves the boundary value problem. In the motion generation stage, natural-looking walking motion, which includes plane walking, walking upstairs and downstairs and walking on a curved path, is created by applying dynamics and kinematics. The human body is approximated as a simple rigid skeleton model, and dynamic motion is created based on the ground reaction force of the human foot. To adapt to the 3D environment, the 3D walking path is divided into steps which are tagged with the parameters needed for motion generation, and step-by-step motion is connected end-to-end. Additional features include fast calculation and a reduced need for user control. The proposed method can produce interesting human motion and can create realistic computer animation scenes. Copyright © 2000 John Wiley & Sons, Ltd.

When a scene is represented in a binocular stereoscopic display, depth distortions are perceived at the edges of the images in front of the screen. In our previous research (Ishigure et al., ITE, 1996), we showed that adding a virtual frame with a crossed disparity relative to the objects in stereoscopic images can eliminate the distortion. In the present study, we investigated how the depth distortion affects vergence eye movements and whether a virtual frame plays a role. The experimental results show : (1) when subjects perceive a depth distortion, the eyes converge to a point closer to the disparity of the screen than that of the object, (2) when the shape of the distorted object changes, convergence also changes, and (3) when the virtual frame has a crossed disparity, the point of convergence is located at the position indicated by the disparity of the object. The results indicate that presenting a stereoscopic image with an accompanying virtual frame prevents an undesired shift in convergence.

An object that is reproduced by a stereoscopic display is perceived in front of the screen with depth distortion by human observers when the reproduced area of the object is truncated by a picture frame Experimental results suggest that (1) the occlusion condition, which contradicts a real three-dimensional situation (i.e, valid), causes this distortion, (2) observers, who misfuse a binocular image that includes the monocular region perceive the frontal-parallel plane as a slanted one, (3) this misperception is caused because the process of the information synthesis between the pictorial and binocular occlusion cues depend on the binocular disparity sign (i.e, it is caused when real world constraints were not satisfied) We show that adding a virtual picture frame (VFM : virtual frame) in front of the real screen enables human observers to perceive the correct depth.

A neural net approach is proposed to classify the eye shape with the respect to the three dominant features obtained from the subjective evaluation standard. The neural network is composed of eighteen physical features of the eye used as input data and the three features in the subjective tests used as output data. From the experiments, it can be concluded that these features combined can best represent various subjective impressions of human eyes. It can also be shown that unknown data can be classified by using k-neighbor interpolation training, where neighboring data are chosen based on the criterion of absolute standard of learning data.

When a black or white rectangle drifts horizontally across a background of black and white vertical stripes, the rectangle appears to stop and start as it crosses each stripe (the footsteps illusion; Anstis, 2001 Perception 30 785–794). Although previous studies indicate that confusion between contrast and velocity signals in the motion detectors or the spatial pattern of the background contribute to the footsteps illusion (e.g., Sunaga et al., 2008 Perception 37 902–914), it remains unclear which factor is critical. We hypothesize that the contour of the rectangle is significant to the footsteps illusion. A subjective experiment is conducted using modified rectangles, the contour of which were emphasized by adding contour lines, filling random dots inside, or putting illusory contour inducers on the four corners. Two kinds of rectangles were presented above and below central fixation simultaneously and the background strips were scrolled from right to left, or vice versa. Participants were asked which rectangle was perceived to drift more smoothly. The results demonstrate that the footsteps illusion is reduced when the rectangle's contour is emphasized. Placing random dots inside the rectangle yielded a weaker illusion than the rectangle that was surrounded by lines. These results suggest that humans perceive the velocity of moving objects (or background) based on the extracted contours which are constructed by integrating low spatial frequency information.

We present a posture measurement method that uses foot pressure distribution and video camera images. The method first estimates the position, posture and size of subject in the real world from his or her foot pressure distribution. These estimates are represented by a stick model. The position of the skeleton in the camera image is then detected by using the estimated skeleton obtained by projecting the stick model onto the camera image as initial value. We tested this method on 80 walking patterns of eight women. The results show that the detected skeleton lies at the center of the leg.

This paper describes a method that can improve the visibility of features in shadowed regions in urban aerial images while retaining nonshadowed regions and the natural tint of shadowed regions automatically. The method first calculates the posteriori probabilities of each pixel belonging to shadowed class or nonshadowed class using color features from a low-frequency component image, and then compensates the intensity and saturation of each pixel in shadowed regions according to the posteriori probabilities. Experimental results indicate the effectiveness of proposed method.

Two eyes' views together contain more spatial or geometric information than what can be represent faithfully from one vantage point. Just as it is impossible to paint an "authentic" picture on canvas, it is impossible for the visual system to make a "faithful visual" picture. We conducted several psychophysical experiments using stereoscopic displays. Experimental results on judging direction showed that the visual system solves the problem of fitting the two eyes' views, in their entirety, into a single cyclopean view by "displacing" and "compressing", perceptually, a portion of the visual field. The experimental results on judging shape showed that the visual system has a "correcting" mechanism to adjust for the consequences of the directional displacement and compression. We hypothesize that the operation of this "correcting" mechanism is triggered by the pictoral cue of occlusion and that this mechanism is responsible for the Kanizsa and Poggendorff illusions when three-dimensional stimuli are drawn a sheet of paper.

Land's two-color method gives rise to apparent full-color perception, even though only two colors (e.g., red and gray) are used. Previous studies indicate that chromatic adaptation, color memory, and inductive effects contribute to the shifts of color perception from real to illusory colors (e.g., Kuriki, 2006 Vision Research 46 3055–3066). This paper investigates the relationship between the color shifts induced by Land images and the skewness of the luminance histogram. In Experiment 1, several Land images are created based on a yellow ball, and the magnitude of the color shifts of the images are measured. The results of Experiment 1 show a significant correlation between the magnitude of the color shifts and skewness, suggesting that skewness is critical for the color shifts. In Experiment 2, we test the hypothesis that color shifts depends on just skewness; the color shifts should be invariant even if the Land images are scrambled. However, the results of Experiment 2 demonstrate that scrambled Land images exhibit less intense color shifts, suggesting that color shifts are determined by the object's overall shape or surface gloss, not just skewness. Taken together, we conclude that both low-level visual processes, such as those associated with luminance histogram skew, and high-level cognitive functions, such as object interpretation or understanding of surface gloss, are involved in the color shift of Land images.

We have found a new method in which two overlapped images displayed at different depths can be perceived as an image protruding outside the region of the two images. This enables a deeper 3-D imaging area in the DFD display, when the two images have opposite signs of luminance difference between an object in the images and the surroundings.

When a telewriting signal of handwritten text and graphics shares a common telephone channel with voice, the data rate of the telewriting must be curtailed to maintain the quality of the audio portion. A fixed rate sampling method with linear interpolation has been used in telewriting because of its simplicity. However, this method does not perform well when distortions are caused by higher drawing speed of line strokes. To overcome such a shortcoming, this paper: (1) investigates the distortions associated with the fixed rate sampling method; (2) derives quantitative measures of interpolation distortion and truncation distortion; and (3) proposes an adaptive sampling algorithm. A writing tablet (4 dots/mm resolution) was used in the experiments to validate the objective measures, and to assess the performance of the adaptive algorithm. Experimental results indicate that while the data rates of the fixed rate sampling method and the adaptive method are almost the same, the adaptive method scores higher in the subjective image quality assessment tests.

記入面一体型ディスプレイ, 特に一体型平面ディスプレイは, 画像入力・編集操作性の点から期待を集めているが, その操作性は, 記入点とそれに対応する見かけ上の表示点との視差により大きく影響されると考えられる.本論文では, 記入操作性と視差との関係解明のための基礎資料を得ることを主目的に, 平行な記入・表示面を有する一体型ディスプレイ上で生じ, 感覚受容の対象となる視差の構成要素として “視距離誤差比”, “視線入射角誤差”, “視差平面角” を採り上げ・これらと面間の厚さ・屈折率, 観視位置との関係を, (1) 記入点の垂直下を実際の表示点とする場合, (2) 予想される観視位置条件から視線入射角誤差を補正した場合, (3) 補正後に観視位置条件が変化した場合, について幾何光学的に数値解析し, 視差の基本構造を明らかにするとともに, 今後有望な記入面一体型平面ディスプレイの設計指針を提供している.