Conference Paper 2004 IEEE : Institute of Electrical and Electronics Engineers
An efficient TCP with explicit handover notification for mobile networks(Last author)
モバイルネットワークにおける明示的ハンドオーバー通知による効率的なTCPの実現
Haruki Izumikawa, Ichiro Yamaguchi, Jiro Katto
【抄録】TCP is a popular internet protocol for reliable end-to-end data delivery, but it cannot he directly applied to wireless networks in which packet loss may be induced by higher HER or handover than congestion. TCP assumes that such packet loss is caused by network congestion and initiates congestion control procedures. In this paper, we present a novel protocol using Explicit Handover Notification to improve TCP performance over wireless links. Additionally, we execute computer simulations using network simulator and compare with other various protocols.
【抄録】This paper presents a method of gender classification by integrating facial, hairstyle, and clothing images. Initially, input images are separated into facial, hairstyle and clothing regions, and independently learned PCAs and GMMs based on thousands of sample images are applied to each region. The classification results are then integrated into a single score using some known priors based on the Bayes rule. Experimental results showed that our integration strategy significantly reduced error rate in gender classification compared with the conventional facial only approach.
Article 1999 3 IEEE : Institute of Electrical and Electronics Engineers
System architecture for synthetic/natural hybrid coding and some experiments(First author)
合成/自然ハイブリッド符号化のためのシステム構成といくつかの実験
Jiro Katto, Mutsumi Ohta IEEE Transactions on Circuits and Systems for Video Technology
【抄録】This paper presents a system architecture for synthetic/natural hybrid coding toward future visual services. Scene-description description capability, terminal architecture, and network architecture are discussed by taking account of recent standardization activities: MPEG, VRML, ITU-T, and IETF. A consistent strategy to integrate scene-description capability and streaming technologies is demonstrated. Experimental results are also shown, in which synthetic/natural integration is successfully carried out.
Article 1999 The Institute of Image Information and Television Engineers
“New Techniques in the MPEG-4 Visual Standar ”(Last author)
「MPEG-4ビジュアルスタンダードの新技法 」
Hiroyuki Katata, Yoichi Yagasaki, Toshiaki Watanabe, Jiro Katto Kyokai Joho Imeji Zasshi/Journal of the Institute of Image Information and Television Engineers
Article 1999 IEEE : Institute of Electrical and Electronics Engineers
Structure recovery with multiple cameras from scaled orthographic and perspective views
複数カメラによる縮尺正投影図と透視図からの構造復元
Atsushi Marugame, Jiro Katto, Mutsumi Ohta IEEE Transactions on Pattern Analysis and Machine Intelligence
【抄録】This paper presents a novel framework for Euclidean structure recovery utilizing a scaled orthographic view and perspective views simultaneously. A scaled orthographic view is introduced in order to automatically obtain camera parameters such as camera positions, orientation, and focal length. Scaled orthographic properties enable all camera parameters to be calculated implicitly and perspective properties enable a Euclidean structure to be recovered. The method can recover a Euclidean structure with at least seven point correspondences across a scaled orthographic view and perspective views. Experimental results for both computed and natural images verify that the method recovers structure with sufficient accuracy to demonstrate potential utility. The proposed method can be applied to an interface for 3D modeling, recognition, and tracking.
Conference Paper 1998 IEEE : Institute of Electrical and Electronics Engineers
Runlength-based wavelet coding with adaptive scanning for low bit rate environment
低ビットレート環境における適応走査を用いたランレングスベース・ウェーブレット符号化
Takahiro Kimoto, Jiro Katto, Mutsumi Ohta IEEE International Conference on Image Processing
【抄録】A new wavelet coding method is presented to exploit both intra/inter-band correlations. While the traditional zerotree approach can exploit correlation between subbands, a wavelet decomposition has properties more suitable for the runlength coding method, which can exploit spatial correlation. The proposed method classifies wavelet coefficients into groups according to their parents' magnitude. Each group is chosen in order of the magnitude and scanned to keep spatial correlation. It outperforms the zerotree-based coding approach especially at low bit rate.
Improved scanning methods for wavelet coefficients of video signals
映像信号のウェーブレット係数の走査方法の改善
Fabrice Rossetti, Jiro Katto, Mutsumi Ohta Signal Processing: Image Communication
【抄録】This paper describes novel methods to improve coding efficiency of the wavelet transform from the viewpoint of scanning techniques. Firstly, statistical properties of the wavelet transform are examined using real image sequences. They indicate energy distribution or correlations of wavelet transformed coefficients. Taking them into account, efficient scanning methods are investigated for two different approaches. The first approach treats transform coefficients, located in spatially neighboring position, in 8 × 8 blocks. This is called block based approach, and its optimum scanning path is examined similar to the zigzag scan for DCT (discrete cosine transform). Furthermore, a new scanning algorithm utilizing correlation between transform coefficients is proposed. The second approach carries out scanning over the entire subimage created by the wavelet transform. This is called subband based approach, in which scanning is applied to each subband. A new scanning algorithm is presented utilizing a block-wise non-linear filter which removes isolated non-zero coefficients. Simulations are carried out, and their results show the effectiveness of the above approaches especially for low bit-rate applications.
Conference Paper 1996 IEEE : Institute of Electrical and Electronics Engineers
Mathematical analysis of MPEG compression capability and its application to rate control(First author)
MPEG圧縮能力の数理解析とレートコントロールへの応用
Jiro Katto, Mutsumi Ohta IEEE International Conference on Image Processing
【抄録】This paper presents mathematical frameworks on temporal predictive processing in the MPEG video compression standard. Firstly, a coding gain is derived based on traditional prediction theories. The optimum ordering of three different picture types (I,P,B-pictures) is clarified according to image source characteristics. Secondly, a novel framework on the target bit assignment is presented with some experimental backgrounds. The solution consists of simple formulae, but brings drastic SNR gains to the conventional TM5 algorithm.
Conference Paper 1996 IEEE : Institute of Electrical and Electronics Engineers
Novel algorithms for object extraction using multiple camera inputs(First author)
複数カメラ入力を用いた物体抽出のための新規アルゴリズム
Jiro Katto, Mutsumi Ohta IEEE International Conference on Image Processing
【抄録】This paper presents novel algorithms exploiting multiple camera inputs and segmentation techniques, which can be applied to image fusion, disparity detection and object extraction. Differently focused images, stereo pairs and both of them are used for fusion, disparity detection and object extraction, respectively. Firstly, image fusion is done by segmentation of each image and determination of focused regions per segment. An efficient decision criterion is developed taking a method of auto-focus into consideration. Secondly, disparity detection is executed by recursively applying segmentation and disparity detection per segment. A new clustering criterion is proposed in order to achieve good segmentation and high compression ratio of disparity maps simultaneously. Finally, object extraction is carried out by utilizing both the fusion result and the disparity map. Experiments are carried out, and they show us effectiveness of the proposed algorithms.
Conference Paper 1996 IEEE : Institute of Electrical and Electronics Engineers
Structure recovery from scaled orthographic and perspective views
縮小正投影図と透視図からの構造復元
Atsushi Marugame, Jiro Katto, Mutsumi Ohta IEEE International Conference on Image Processing
【抄録】This paper presents a novel framework for structure recovery utilizing a scaled orthographic view and perspective views simultaneously. Perspective views lead to precise recovery based on the triangulation principle; however, many parameters such as camera positions, camera poses and focal length, must be measured beforehand. Thus, a scaled orthographic view is introduced as a subsidiary system to achieve them automatically. Camera parameters ate calculated implicitly owing to the scaled orthographic properties, and then the structure recovery is done by the orthogonality of camera coordinate systems and the triangulation principle. The experimental results provide sufficient accuracy of structure recovery.
Conference Paper 1995 IEEE : Institute of Electrical and Electronics Engineers
Analytical framework for overlapped motion compensation(First author)
オーバーラップ動作補償のための解析的フレームワーク
Jiro Katto, Mutsumi Ohta ICASSP, IEEE International Conference on Acoustics, Speech and Signal Processing - Proceedings
【抄録】This paper presents a novel framework which proves the superiority of overlapped motion compensation. Window design problem is revised by introducing a statistical model of motion estimation process. The result clarifies relationship between the optimum window and image characteristics in an explicit formula and quantifies prediction error reduction achieved by overlapped motion compensation. Experimental results using real image sequences support the proposed theory and demonstrate its superiority. Overlapping in warping prediction is also considered and its effectiveness is shown.