Kazuhiko Yamamoto

Gifu University, Gihu, Gifu, Japan

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Publications (100)1.1 Total impact

  • Kazuya Takahashi, Kunihito Kato, Kazuhiko Yamamoto
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    ABSTRACT: The purpose of this study is to construct a model of an optical lens by using a multi camera array. It is known that virtually focused images can be produced by synthetic aperture focusing techniques. However there is a difference between the blur of the virtually focused image and the blur of an image produced by an optical lens. We suggest a method to correct this difference. Using our method, it is possible to create images that have multiple discrete focus depths, something that is impossible using an optical lens. Basic experiments were conducted, and the effectiveness of the approach was demonstrated.
    Proc SPIE 06/2011;
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    ABSTRACT: It is difficult to analyze how human feels deliciousness by seeing served food because many factors affect to judgment of deliciousness. Human recognizes and evaluates deliciousness of the food from many points of view. In this paper, we propose a method to extract the points of view and factors that recognize deliciousness. Images which are reduced resolution to control information of the image were provided to the subjects. At low resolution images, we cannot see many factors which can be recognized at higher resolution, and we judge deliciousness from the only factor which can be recognized. We show the effectiveness of our proposed method for applying the box lunch.
    01/2011;
  • Shohei Suzuki, Kunihito Kato, Kazuhiko Yamamoto
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    ABSTRACT: A text reader for mobile phone has a problem that the camera position is matched to a line in documents hardly. In this paper, we propose "Nail Camera System" by using character recognition to solve this problem. This system has an advantage that the position of the camera is matched to a line easily because the user attaches a small camera to user's finger. Additionally, a line can be traced by simple and natural motion of the finger. However, obtained image from this system is often distorted, because users' motion and angle of the finger is not stable. Therefore, in our method, four directional feature fields are used as a feature extraction method for character recognition. The effectiveness of our proposed approach is described with experimental results. Keywords-Nail Camera System; character recognition; four directional feature fields; character distortion
    01/2011;
  • Kensuke Tobitani, Kunihito Kato, Kazuhiko Yamamoto
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    ABSTRACT: In this study, we focused on the basic taste stimulation for the analysis of real facial expressions. We considered that the expressions caused by taste stimulation were unaffected by individuality or emotion, that is, such expressions were involuntary. We analyzed the movement of facial muscles by taste stimulation and compared real expressions with artificial expressions. From the result, we identified an obvious difference between real and artificial expressions. Thus, our method would be a new approach for facial expression recognition.
    IEEJ Transactions on Industry Applications 01/2011; 131:586-591.
  • Kensuke Tobitani, Kazuhiko Yamamoto, Kunihito Kato
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    ABSTRACT: In this study, we are concerned with calligraphy education support system. In current calligraphy education in Japan, teachers evaluate character written by students and they teach correct writing process based on the evaluation of the written character. Professionals in calligraphy can estimate writing process of character and balance of character which are important points for evaluation of character by estimating movement of contact shape (contact faces with paper and brush). But it takes a lot of time for students to be able to learn how to write correct character in this education way. If teachers and students can know movement of the contact shape, calligraphy education will be more efficient. However, it is difficult to detect contact shape from an images captured by cameras set in general angle. Because brush and ink are black either. So, contact shape is hided under the brush. In this paper, we propose new camera system consists of four Horizon View Cameras (HVC) which are special camera setting to detect and reconstruct contact shape, experiment with this system, and compare movement of contact shape of professionals and amateurs.
    IEEJ Transactions on Electronics Information and Systems 01/2009; 129(5):786-791.
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    ABSTRACT: Many active safety technologies for the driver support system are developing. Most traffic accidents are caused by the driver's inattentiveness or drowsiness. We are developing a driver support system that protects against traffic accidents due to these causes. Our purpose is to detect the driver's face region with a camera. Many face detection methods are proposed, but there is no technique addressing every environment inside the car. For example, skin color segmentation cannot detect the skin region in the night, because it has to light up the driver by bright light. In this paper, we propose a skin detection method using the unique reflection characteristics of the materials. Our method is a very simple algorithm. We developed a skin detection system, and confirmed its effectiveness by an evaluation experiment in an indoor environment, and showed its effectiveness by a nighttime driving experiment. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(11): 19–27, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10149
    Electronics and Communications in Japan 01/2009; 92(11):19-27. · 0.18 Impact Factor
  • Hirotaka Ohta, Kazuhiko Yamamoto
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    ABSTRACT: When character recognition is made from low-resolution characters of motion image, it is the general idea to restructure high-resolution image first by using sequence of the low-resolution images and then extract features from the constructed high-resolution image. In this paper, we propose a new method in which the direct extraction of features from the low-resolution images is made first, and then reconstructing high accuracy feature from sequence of the feature. We show the advantage of our proposed method over ordinary method on theoretical and recognition experiment.
    IEEJ Transactions on Electronics Information and Systems 01/2009; 129(5):963-969.
  • Source
    Kunihito Kato, Masayuki Shamoto, Kazuhiko Yamamoto
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    ABSTRACT: In this research, we considered that "the humanoid robot has to have humanoid functions", and eyes for humanoid robot have to be "Humanoid Vision". Therefore, we analyzed the human action of tracking an object by the eyes and implemented the obtained features to a humanoid robot "YAMATO". From implementation results, we showed the effectiveness of humanoid vision. Our future works are analysis of longitudinal movement and complicated movements to movement of a robot.
    11/2008; , ISBN: 978-953-7619-21-3
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    ABSTRACT: Nowadays, many evaluation methods for food industry by using image processing are proposed. These methods are becoming new evaluation method besides the sensory test and the solid-state measurement that have been used for the quality evaluation recently. The goal of our research is structure evaluation of sponge cake by using the image processing. In this paper, we propose a feature extraction method of the bobble structure in the sponge cake. Analysis of the bubble structure is one of the important properties to understand characteristics of the cake from the image. In order to take the cake image, first we cut cakes and measured that's surface by using the CIS scanner, because the depth of field of this type scanner is very shallow. Therefore the bubble region of the surface has low gray scale value, and it has a feature that is blur. We extracted bubble regions from the surface images based on these features. The input image is binarized, and the feature of bubble is extracted by the morphology analysis. In order to evaluate the result of feature extraction, we compared correlation with "Size of the bubble" of the sensory test result. From a result, the bubble extraction by using morphology analysis gives good correlation. It is shown that our method is as well as the subjectivity evaluation.
    Proc SPIE 05/2007;
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    ABSTRACT: This paper proposes a method to detect moving objects by the background subtraction using the normalized correlation matching. The normalized correlation matching is known as one of general-purposed template matching methods. And the method is robust against change of brightness. Therefore, it is expected that the stable detection of moving objects will be performed by using the normalized correlation matching against changing brightness of background. The proposed method regards the background image as the template image and evaluates correlation rates between the background image and the scene image in order to extract moving objects. We also adopt the integration technique of the correlation rate to realize more stable detection.
    Proc SPIE 05/2007;
  • Liwen Gong, Kazuhiko Yamamoto, Kunihito Kato
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    ABSTRACT: In this paper, we described various properties of a Generalized Horizon View Camera (GHVC). Original Horizon View Camera (HVC) is a optical system composed of a camera and a mirror. HVC put a single camera on the ground, and the optical axis of the camera is set on the horizon by a mirror. HVC can obtain two kinds of images. One is the image including only objects on the ground in front of the HVC. The other image is including just in front of the HVC. Therefore, it is possible to detect object easily. The GHVC is able to improve a degree of freedom of HVC. In this experiment, we measured a distance to an object by the GHVC. We confirmed that detecting object using the GHVC was effective.
    IEEJ Transactions on Electronics Information and Systems 01/2007; 127(12):2011-2017.
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    ABSTRACT: Many active safety technologies for the driver support system are developing. Most of the traffic accidents are caused by driver's inattentive or drowsy. We are developing a driver support system that protects from traffic accidents by these causes. Our purpose is to detect the driver's face region by using a camera. A lot of face detection methods are proposed, but there is not a technique addressing every environment inside the car. For example, skin color segmentation can not detect the skin region in the night, because it has to light up the driver by bright light. In this paper, we propose a skin detection method by the unique reflection characteristics of the materials. Our method is very simple algorithm. We developed a skin detection system, and confirmed effectiveness by the evaluation experiment in indoor environment, and showed the effectiveness by a driving experiment in the night.
    IEEJ Transactions on Electronics Information and Systems 01/2007; 127(4):583-590.
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    ABSTRACT: Detection of skin region is one of the important process of the face detection. Skin region is usually detected by using the skin color. However, the method has some problems which are influence of lighting condition and etc. The methods are defined the skin color in visible optical band. The method should illuminate visible light in the dark place. Therefore we paid attention to difference of the reflectance characteristic of materials. We proposed a skin detection method directly by the reflection characteristic. In this paper, we propose a method to reduce influences of the environment light by using one band pass filter. The usefulness is confirmed by a skin detection experiment.
    Proc SPIE 01/2007;
  • Source
    Liwen Gong, Kazuhiko Yamamoto, Kunihito Kato
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    ABSTRACT: In this paper, we propose Generalized Horizon View Camera system. It can able to improve a degree of free- dom of Horizon View Camera (HVC) while keeping characteristics of previous HVC by using a horizon that existed at a center of camera lens. In this paper, we measured a distance to the object by the obtained image actually. In this experiment, we confirmed that detecting object using the GHVC is effective.
    Proceedings of the IAPR Conference on Machine Vision Applications (IAPR MVA 2007), May 16-18, 2007, Tokyo, Japan; 01/2007
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    ABSTRACT: Nowadays, many evaluation methods for food industry by using image processing are proposed. These methods are becoming new evaluation method besides the sensory test and the solid-state measurement that have been used for the quality evaluation recently. The goal of our research is structure evaluation of sponge cake by using the image processing. In this paper, we propose a feature extraction method of the bobble structure in the sponge cake. Analysis of the bubble structure is one of the important properties to understand characteristics of the cake from the image. In order to take the cake image, first we cut cakes and measured that's surface by using the CIS scanner, because the depth of field of this type scanner is very shallow. Therefore the bubble region of the surface has low gray scale value, and it has a feature that is blur. We extracted bubble regions from the surface images based on these features. The input image is binarized, and the feature of bubble is extracted by the morphology analysis. In order to evaluate the result of feature extraction, we compared correlation with "Size of the bubble" of the sensory test result. From a result, the bubble extraction by using morphology analysis gives good correlation. It is shown that our method is as well as the subjectivity evaluation.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
    12/2006;
  • Ayami Iwata, Kunihito Kato, Kazuhiko Yamamoto
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    ABSTRACT: We have proposed Horizon View Camera (HVC), which is a unique system of the object detection by a single camera and has some unique characteristics. HVC is to put a single camera on the ground, and the optical axis of the camera is directed toward the horizon by using a mirror. HVC can obtain two kinds of images. One is the image including only the object on the ground. Therefore, it is possible to detect objects easily. We have shown its effectiveness by measuring distances to objects using the obtained images from HVC with straight motions. Moreover, we proposed HVC-90 that is more effective system than the original HVC for object detection. HVC-90 can detect objects in various motions. In these camera systems, we used characteristics obtained from moving HVC mainly. In this paper, moreover, we develop a unique input interface by using characteristics from standing HVC. We made a potable piano as an example of this interface, and show its effectiveness.
    IEEJ Transactions on Electronics Information and Systems 01/2006; 126(1):44-50.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Many active safety technologies for the driver support system are developed. Most of the traffic accidents are caused by driver’s inattentive or drowsy. We are developing a driver support system that protects from traffic accidents by these causes. Our purpose is to detect the driver’s face region. A lot of face detection methods are proposed, but there is not a technique addressing every environment inside the car. In this paper, we propose a skin detection method by the unique reflection characteristics of the materials. We developed the skin detection system, and confirmed the effectiveness by the evaluation experiment.
    Computer Vision - ACCV 2006, 7th Asian Conference on Computer Vision, Hyderabad, India, January 13-16, 2006, Proceedings, Part II; 01/2006
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    ABSTRACT: Moving object detection with a mobile image sensor is an important task for mobile surveillance systems running in real environments. In this paper, we propose a novel method to effectively solve this problem by using a Stereo Omni-directional System (SOS), which can obtain both color and depth images of the environment in real time with a complete spherical field of view. Taking advantage of the SOS that the frame-out problem never occurs, we develop a method to detect the regions of moving objects stably under arbitrary movement and pose change of the SOS, by using the spherical depth image sequence obtained by the SOS. The method first predicts the depth image for the current time from that obtained at the previous time and the ego-motion of the SOS, and then detects moving objects by comparing the predicted depth image with the actual one obtained at the current time.
    Formal Pattern Analysis & Applications 01/2006; 9:113-126. · 0.81 Impact Factor
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    ABSTRACT: Moving object detection with a mobile image sensor is an important task in robotics and computer vision, when considering the practical use of robotics in human environments. In this paper, we propose a robust method that detects moving objects in the environment using the omnidirectional depth information obtained by a mobile Stereo Omnidirectional System (SOS). In order to detect only the moving objects within the depth image that are obtained by a sensor in motion, we first estimate the ego-motion of the sensor, and generate a predicted depth image for the current time from the depth obtained at the previous time by only considering the ego-motion of the sensor. Then the predicted depth image is compared with the actual one obtained at the current time, and the inconsistent regions are detected as moving objects. When the sensor moves, occlusions will occur in the scene and they will cause false detections. However, these false detections can be suppressed by estimating the occlusion regions using the ego-motion parameters of the sensor and the jump edges in the depth image. The effectiveness of the method is shown with experimental results for a real environment. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(3): 29–38, 2005; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/eej.20155
    Electrical Engineering in Japan 06/2005; 152(3):29 - 38. · 0.10 Impact Factor
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    ABSTRACT: In this paper, the authors propose a new technique for robust location and pose estimation for an active vision sensor using images obtained by a camera system (omnidirectional sensor) that can acquire panoramic information of the environment. The proposed technique first calculates a panoramic edge histogram in advance from images obtained by the omnidirectional sensor at several reference points in the environment. To estimate the sensor location and pose, dynamic programming (DP) is extended to two-pass DP, and the current location is matched with the panoramic edge histogram at the reference points to obtain the edge shift magnitude at each direction angle. These shift magnitudes have the same periodicity as a sine curve, the sensor rotation corresponds to the offset of the sine curve, and its movement direction corresponds to the 0-phase of the sine curve. In the current research, the sensor's movement direction and rotation angle are efficiently estimated by independently fitting the offset and the 0-phase of its period from these edge shift magnitudes. Finally, the exact location is calculated from the movement directions for the two closest reference points. The effectiveness of the proposed technique is shown by experiments in an actual environment. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(14): 32–43, 2004; Published online in Wiley InterScience (). DOI 10.1002/scj.10699
    Systems and Computers in Japan 01/2004; 35:32-43.