映像情報メディア学会誌
Online ISSN : 1881-6908
Print ISSN : 1342-6907
ISSN-L : 1342-6907
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62 巻, 4 号
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次世代医療を担う最新映像技術
1. 次世代医療を担う医用画像工学
2. 医用画像センシング
3. 三大疾患診断の中で医療用X線CT装置がはたす役割
4. ナビゲーション型知的診断支援システム
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論文小特集　3次元映像情報メディア技術
小特集論文
  • CGを利用したCGHの隠面処理改善とディスクホログラムへの応用
    藤井 知彦, 山口 健, 吉川 浩
    2008 年 62 巻 4 号 p. 527-532
    発行日: 2008/04/01
    公開日: 2010/05/01
    DOIhttps://doi.org/10.3169/itej.62.527
    ジャーナル フリー
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    For practical 3-D computer-generated holograms (CGH), it is important to display surface model shaded images like computer graphics (CG). We have developed a simple process that is used to obtain 3-D data for CGH from two CG images. The first image is a shaded CG image. The second image is a depth-cued image, i.e., image intensity is modulated by the depth of the object. We use a Z-buffer, which is usually used for hidden-surface removal, to make the depth-cued image. We have improved the process to eliminate the problem of the absence of the hidden surface's data, which should appear when a viewer moves. We adapted our process so that it can be used to make a master disk hologram, meaning that, CGHs from processed 3-D Data are displayed on a disk hologram.
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  • 外部パラメータが未知なカメラの多視点映像による移動体のフローモーション生成法
    和田 稔, 伊藤 浩, 杉本 和夫, 山岸 秀一, 小林 翼
    2008 年 62 巻 4 号 p. 533-544
    発行日: 2008/04/01
    公開日: 2010/05/01
    DOIhttps://doi.org/10.3169/itej.62.533
    ジャーナル フリー
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    We have developed a new flow-motion generation method that links the scaling and translation parameters of multi-view images with the position of a moving object in those images. Instead of calibrating extrinsic parameters, we used homographies between flat floors in images taken by each cameras, vanishing points in the vertical and horizontal directions, and the size of a reference object which was shot beforehand. We combined our new system with a system that tracks the positions of moving objects from multi-view images and demonstrated the flow-motion of moving objects.
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  • 擬似高解像度化によるホログラムの水平視域角拡大
    林 勇樹, 高木 康博
    2008 年 62 巻 4 号 p. 545-549
    発行日: 2008/04/01
    公開日: 2010/05/01
    DOIhttps://doi.org/10.3169/itej.62.545
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    We developed a new technique that enables the ratio of horizontal and vertical resolutions of a spatial light modulator (SLM) to be altered. This technique virtually increases the horizontal resolution of an SLM so that the horizontal viewing angle of a hologram displayed by the SLM is also increased. An SLM illuminated by a slanted point light source array is imaged by a 4f imaging system in which a horizontal slit is located on a Fourier plane. When the number of point light sources is K, the horizontal resolution increases K times and the horizontal viewing angle increases approximately K times. We demonstrated the horizontal viewing angle enlargement using an SLM with a pixel pitch of 9.5 µm and a resolution of 4,096×2,160. The number of light sources was four (K = 4.) The horizontal resolution was increased to 16,384 and the horizontal viewing angle was increased to approximately 15°. The resultant three-dimensional images can be observed by both eyes.
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  • 奥行きモデルを用いた擬似広視野映像の実時間生成
    本多 健二, 橋本 直己, 佐藤 誠
    2008 年 62 巻 4 号 p. 550-557
    発行日: 2008/04/01
    公開日: 2010/05/01
    DOIhttps://doi.org/10.3169/itej.62.550
    ジャーナル フリー
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    Interactive contents with high quality images is now widely available. One way to make this content more realistic is to display it covering the viewer's entire field of view. The problem is that the view-angle of the existing content is not adequate for large display surfaces because the content is designed to be displayed on household TV monitors with a target view-angle of approximately 30 degrees. To achieve realism, we have to enlarge the view-angle of these images in real-time. Therefore, we developed a technique that reconstructs wide view-angle images by extracting peripheral images from time-series image frames in real-time. A simple 3-D model approximating target scenes enables real-time processing and a reduction of the uncomfortable feeling that happens when reconstructed peripheral images are distorted. We used our method with actual game content and objectively and subjectively evaluated the image quality and processing time. The evaluation results demonstrated that our technique effectively enhanced the fun of content itself.
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  • 没入型仮想環境における力覚提示ウィジェット用いた移動タスクの評価
    Marc Salvati, Naoki Hashimoto, Makoto Sato
    2008 年 62 巻 4 号 p. 558-563
    発行日: 2008/04/01
    公開日: 2010/05/01
    DOIhttps://doi.org/10.3169/itej.62.558
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    We developed haptic enabled widgets for immersive environment: the HapWi concept. It enables task mode switching, and intuitive interaction with a virtual environment. In this paper we present a comparative study of our interaction method and a keyboard based interaction method with locomotion tasks. With our virtual widgets, the user can perform in a immersive environment context as well as with a keyboard (in the same immersive environment), even for a task that is really designed for keyboard users. A study of haptic feedback will demonstrate the need for the user to understand and stabilize his actions in the virtual world and will emphasizes the need to adapt haptic rendering to individual specificity.
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  • 特徴点軌跡並行化による2次元カメラアレイレクティフィケーション
    福嶋 慶繁, 松本 健太郎, 圓道 知博, 藤井 俊彰, 谷本 正幸
    2008 年 62 巻 4 号 p. 564-571
    発行日: 2008/04/01
    公開日: 2010/05/01
    DOIhttps://doi.org/10.3169/itej.62.564
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    We have developed an effective rectification method that has a pixel error of less than 0.25 of a pixel for use in two-dimensional multi-camera arrays. Rectification and correction are important for free view-point imaging and multi-view coding in the field of image-based rendering (IBR). In the computer vision field, a number of rectification methods for binocular/trinocular stereo camera setups have been develpopd and used. However, not many multi-camera array rectifications methods have been developed.
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論文
  • デジタル放送向け動画像符号化における低遅延化技術の開発と性能評価
    岡田 信一, 本山 信明, 小原 英司, 大澤 淳真, 小野 みどり, 服部 伸一, 浅野 研一
    2008 年 62 巻 4 号 p. 578-586
    発行日: 2008/04/01
    公開日: 2010/05/01
    DOIhttps://doi.org/10.3169/itej.62.578
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    We have developed a low delay video coding technique for use in digital broadcasting of HDTV format pictures. We developed a delay model that analyzes processing time of requisites for video codec. This delay model explicates a general codec delay from encoding-top to decoding-end in 600.8ms and mainly depends on preprocessing and sending and receiving buffers. Based on this model, we develop a technique that reduces the delay of 600.8 to 250ms. We tested our technique using a hardware encoder that operated on a FPGA platform at an operating frequency of 135MHz. This encoder showed a delay of 252ms using a consumer set top box as a decoder.
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  • 番組視聴時の視線分布と番組内容理解度の関係
    澤畠 康仁, 小峯 一晃, 比留間 伸行, 伊藤 崇之, 渡辺 誓司, 鈴木 祐司, 原 由美子, 一色 伸夫
    2008 年 62 巻 4 号 p. 587-594
    発行日: 2008/04/01
    公開日: 2010/05/01
    DOIhttps://doi.org/10.3169/itej.62.587
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    We investigated the relationship between viewer comprehension of a TV program and the direction of his or her gaze in a real experimental TV educational program involving 26 elementary schoolchildren. The aim was to observe the correlation between TV program comprehension and entropy of gaze distribution. Gaussian Mixture Models (GMM) are estimated using statistical methods and assumed to represent the distribution of many subjects' gaze. The results indicate that variances in gaze direction tended to be lower for scenes for which the subjects had better comprehension. The tendency was further noticeable after keywords were uttered that were related to the answers of correponding questions. A gaze-model-estimation method and the theretical accuracy are also described in the paper.
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  • 学年別ルビ付加機能を有するソフトウェアを利用した発話内容提示システムの構築と評価
    小林 正幸, 西川 俊, 三好 茂樹, 石原 保志
    2008 年 62 巻 4 号 p. 595-605
    発行日: 2008/04/01
    公開日: 2010/05/01
    DOIhttps://doi.org/10.3169/itej.62.595
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    Using Microsoft Word and software that displays pronunciation alongside kanji characters, we have constructed and evaluated a system that presents speech content using sentences containing kana and kanji characters that are presented with pronunciation alongside each kanji character on a stenography keyboard. The pronunciation displayed can be set to match a reader's literacy level in Japanese so that only pronunciation is displayed for kanji that the reader does not know how to pronounce. The paper contains a description of the functions, characteristics, and speech content presentation methods of the system. As part of our efforts to provide good comprehension to hearing-impaired students using the system, we used the system in a lecture. After the lecture, we distributed questionnaires to the hearing-impaired students to inquire about the effectiveness of the system. By analyzing the questionnaire results, we were able to verify the system's effectiveness and usefulness. When Chinese characters are used in the Japanese language they are generally referred to as kanji to avoid confusion.
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  • ステップバリア方式立体ディスプレイ
    増谷 健, 安東 孝久, 金山 秀行, 高橋 秀也
    2008 年 62 巻 4 号 p. 606-610
    発行日: 2008/04/01
    公開日: 2010/05/01
    DOIhttps://doi.org/10.3169/itej.62.606
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    We improved the image quality of a 3D display by using a step-barrier system. Conventional parallax barrier systems only reduce horizontal resolution; however, the offset structure of a step barrier system distributes the resolution reduction in both horizontal and vertical directions. This was demonstrated by analyzing the Nyquist frequency of the primary colors on one view-point image. Next, by defining the pixel unit, the resolution of each viewpoint image was evaluated. Then, by formulization of the relation between the number of view points and the image quality, an improvement in the resolution balance was proved. Moreover, in a multi-view display, moire can be removed by using a slanting stripe structure instead of an offset structure. A slanting stripe structure removes the non-uniformity of brightness due to the diffraction at the tiny apertures.
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研究速報
  • 回転プリズムシートによる高画質化Integral Videographyに関する研究
    寺口 剛仁, 松宮 潔, 正宗 賢, 土肥 健純, 廖 洪恩
    2008 年 62 巻 4 号 p. 572-577
    発行日: 2008/04/01
    公開日: 2010/05/01
    DOIhttps://doi.org/10.3169/itej.62.572
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    Integral videography (IV) is a method for displaying animated 3D autostereoscopic images using a combination of a lens array and a number of calculated elemental images with different perspectives. The advantage of IV is that it can be observed from an arbitrary viewpoint without the use of supplementary glasses or tracking devices. We improved the viewing resolution of IV images with a time-sharing technique that involves placing a pair of rotated prism sheets in front of an IV display. Rotating the pair of prism enables parallel-shifts of the light rays in the 3D space around their original positions. The elemental images are displayed and updated according to the cycle of the rotation. We demonstrated the effectiveness of the method using a set of test patterns and modulation transfer functions.
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