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[Author] Yasuhiro OHTAKI(4hit)

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  • Estimation of Color Images by Box Splines from Their Observation through Honeycomb Color Filter

    Tomoko YOKOKAWA  Masaru KAMADA  Yasuhiro OHTAKI  Tatsuhiro YONEKURA  

     
    PAPER-Digital Signal Processing

      Vol:
    E89-A No:12
      Page(s):
    3678-3684

    An experimental test has been done on the suitability of box splines for the estimation of color images from their observation through the honeycomb color filter. The estimation is made by following the framework of consistent sampling by Unser and Aldroubi. Numerical evaluation of the estimation errors has shown that the best estimation may be made by choosing the box splines which are twice locally averaged along each of the three axes consisting of the unilateral triangular mesh. A close look at estimated images has indicated that those box splines are almost free from directional jaggy noises that the traditional B-splines suffer from.

  • Three-Dimensional Measurement Approach for Seal Identification

    Ryoji HARUKI  Marc RIOUX  Yasuhiro OHTAKI  Takahiko HORIUCHI  Kazuhiko YAMAMOTO  Hiromitsu YAMADA  Kazuo TORAICHI  

     
    PAPER

      Vol:
    E78-D No:12
      Page(s):
    1642-1648

    This paper proposes a new approach to deal with the various quality of the reference impressions by measuring the seal to register as 3D (three-dimensional) image, that is, range image. By registering a seal as 3D image, it becomes possible to construct various 2D impressions from it according to the affixing conditions of the reference impression such as the affixing slant, the affixing pressure, the state of the ink on the seal surface and so on. Then, the accurate and easy identification of the seals will be possible by comparing the constructed impression with the reference impression. The performance is verified by experiment, and the result shows that plural 2D impressions according to the affixing conditions can be constructed from only one 3D image of the registered seal.

  • A Network Game Based on Fair Random Numbers

    Masaru KAMADA  Kaoru KUROSAWA  Yasuhiro OHTAKI  Shusuke OKAMOTO  

     
    PAPER

      Vol:
    E88-D No:5
      Page(s):
    859-864

    A compromising technique is proposed for deterring clients from cheating by robot players in skill-based real-time network games. This technique is to inject a fair random noise into the manual input for a real-time game modeled as a chaotic dynamical system. The fair random noise is determined by means of the bit commitment protocol so that neither host nor client can control the noise in their favor. A scenario possibly plotted by a robot player for its victory may be spoiled by slight noise injection because of the sensitivity of chaotic systems to the input. The noise injection brings a luck-based factor into a skill-based game. In this sense, the technique proposed in this paper is not a solution but a compromise for the inherent problem of robot players with the skill-based network games. An example implementation of pinball is presented.

  • A Scheme for Partial Disclosure of Transaction Log

    Yasuhiro OHTAKI  Masaru KAMADA  Kaoru KUROSAWA  

     
    PAPER-Application

      Vol:
    E88-A No:1
      Page(s):
    222-229

    To investigate cyber-criminals, Police sometimes asks Administrator of a computer system to disclose the whole transaction log. Administrator, however, wants to protect the privacy of innocent users. This paper presents a solution for the disclosure/privacy problem of transaction log. In this scheme, Police can search over the encrypted records of the transaction log by keywords. The administrator discloses only the records which include the keyword, but nothing more. Police can verify that the administrator faithfully disclosed all the records which include the keyword.