掲載種別：研究論文（学術雑誌）   出版者・発行元：Institute of Electronics, Information and Communications Engineers (IEICE)  

DOI： 10.1587/transinf.2019pcp0006

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Institute of Electrical and Electronics Engineers Inc.  

For 3D Lambertian scenes with no occlusion, we show that there exist a filter bank such that it can perfectly reconstruct the light field from the focal stack, if the focal stack is captured through 'Cauchy-type' aperture mask. All the derived filters are spatially invariant
therefore the presented filter bank method requires no depth estimation. Simulation results using a synthetic scene show that the filter bank reconstructs the light field with significant high quality.

DOI： 10.23919/APSIPA.2018.8659454

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

Recently, non-fixed camera-based free viewpoint sports video synthesis has become very popular. Camera calibration is an indispensable step in free viewpoint video synthesis, and the calibration has to be done frame by frame for a non-fixed camera. Thus, calibration speed is of great significance in realtime application. In this paper, a fast self-calibration method for a non-fixed camera is proposed to estimate the homography matrix between a camera image and a soccer field model. As far as we know, it is the first time to propose constructing feature vectors by analyzing crossing points of field lines in both camera image and field model. Therefore, different from previous methods that evaluate all the possible homography matrices and select the best one, our proposed method only evaluates a small number of homography matrices based on the matching result ofthe constructed feature vectors. Experimental results show that the proposed method is much faster than other methods with only a slight loss of calibration accuracy that is negligible in final synthesized videos.

Web of Science

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担当区分：筆頭著者  

DOI： 10.14923/transinfj.2015JDP7025

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

Scene refocusing and free viewpoint image reconstruction from a dense light field acquired by a massive camera array or a lens array are actively studied. However, it is difficult to directly integrate acquired information into a light field without defects. For example, actually, a massive camera array hardly works without failure of several cameras, and part of multi-view images are missing. On the other hand, because a lens array consists of very small lenses gathering only limited rays, acquired images themselves are often noisy. This paper proposes simple linear filters achieving view/image restoration to obtain a dense light field robustly in suppressing such defects without block matching used by the conventional approaches of view synthesis and denoising. Experimental results show that the proposed filters can be flexibly designed for various defects based on the relation between a 4D light field and the corresponding 3D multi-focus images.

Web of Science

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

Scene refocusing beyond extended depth of field for users to observe objects effectively is aimed by researchers in computational photography, microscopic imaging, and so on. Ordinary all-in-focus image reconstruction from a sequence of multi-focus images achieves extended depth of field, where reconstructed images would be captured through a pinhole in the center on the lens. In this paper, we propose a novel method for reconstructing all-in-focus images through shifted pinholes on the lens based on 3D frequency analysis of multi-focus images. Such shifted pinhole images are obtained by a linear combination of multi-focus images with scene-independent 2D filters in the frequency domain. The proposed method enables us to efficiently synthesize dense 4D light field on the lens plane for image-based rendering, especially, robust scene refocusing with arbitrary bokeh. Our novel method using simple linear filters achieves not only reconstruction of all-in-focus images even for shifted pinholes more robustly than the conventional methods depending on scene/focus estimation, but also scene refocusing without suffering from limitation of resolution in comparison with recent approaches using special devices such as lens arrays in computational photography.

DOI： 10.1109/TIP.2013.2273668

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Institute of Image Electronics Engineers of Japan  

本論文では，非因果的内挿予測と直交変換とのハイブリッド符号化を用いたマルチエンコード選択型の符号化方式を提案する．提案方式は，直交変換と量子化順序の組合せにより11種類のモードを設定し，ブロックごとに符号化誤差電力が最小となるモードを選択する．実験により，実現したい所要符号量によって直交変換の優劣が変動することを確認し，複数のモードから選択的に符号化を行うことの有効性を示した．その上で，従来ハイブリッド符号化方式において用いられてきたゾーナルサンプリングを，空間領域でのサブサンプリング処理にまで拡張できることを示し，所要符号量の制御に有効であることを示した．さらに，H.264 (High Complexity Mode) に比べて，提案方式はPSNRで最大約6 dB 程度の画質改善があることを確認した．特に，提案方式では，精細部分での画質の改善があること，高ビットレートにおいて特性改善が顕著であることが示された．

DOI： 10.11371/iieej.42.345

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：画像電子学会  

本論文では，帰還差分量子化に基づく内挿予測と直交変換を組み合わせたハイブリッド符号化方式を提案する．直交変換にはH.264と同様にDCTを用いる．提案方式では，ブロックごとに内挿予測誤差を算出し，それをDCTした信号に対して帰還差分量子化を行う．量子化の際，低次成分を先に量子化し，その後は高次成分から量子化する順序変更と符号化誤差の増加率に基づいた量子化ステップを変更を導入する．本手法により，直交変換による信号電力の集中を実現し，高次成分の切捨てによる符号量の削減が可能であることを示す．計算機実験では，空間領域における帰還差分量子化法に比べて最大で2dBの品質改善が達成されることを示す．

DOI： 10.11371/iieej.40.985

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3169/itej.65.372

Scopus

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：画像電子学会  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

This paper deals with a method of generating seriously deformed bokeh on reconstructed images from ordinary multiple differently focused images including just simple bokeh such as Gaussian blurs. We previously proposed scene re-focusing with various iris shapes by applying a three-dimensional filter to the multi-focus images. However, actually the proposed method implicitly assumed that the feature of the iris can be expressed mathematically and it has some symmetry like a horizontally open iris. In this paper, at first, the captured multi-focus images are robustly decomposed into components, each of which goes through its own corresponding pin-hole on the lens, by using dimension reduction and a two-dimensional filter. Then, based on the appropriate composition of the components, reconstruction of arbitrarily deformed bokeh introduced by any user-defined iris is achieved. By some experiments, we show that our novel method can generate even seriously deformed bokeh that does not have simple symmetry. © 2010 IEEE.

DOI： 10.1109/ICIP.2010.5650900

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：The Institute of Image Information and Television Engineers  

An optimal quantization ordering in the feedback quantization scheme for interpolative prediction coding designed to reduce the coding error power is proposed. This method adaptively selects the optimal quantization order to minimize the coding error power from candidate orders for each one dimensional block of 9x1 pixels. These candidate orders can be determined through a numerical analysis of the coding error with respect to all the quantization orders. Simulation results show that the proposed method can effectively reduce the error power and that selecting the optimal order from only four candidate orders can improve the PSNR by about 2 dB, which is just 0.36 dB below the heighest quality image decoded using all 5040 candidate orders. In the case of two-dimensional blocks, although the numerical analysis shows that the coding error power is almost identical among all the possible orders, simulation results demonstrate that selecting the optimal order from four orders in horizontal and vertical directions improves the PSNR by 2.6dB in the case of an 8×8 block.

DOI： 10.3169/itej.63.1652

CiNii Books

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00340281879?from=CiNii

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

In arbitrary viewpoint image synthesis, methods to use shape information of subjects have been widely proposed. However, the shape estimation is generally a time-consuming task, and is not suitable for the real time implementation. In this paper, we focus on the reconstruction filtering method in which arbitrary viewpoint image synthesis is performed without the shape estimation on the assumption that subjects exist on predetermined two planes. We propose an extension of this method to a three (and more)-layered scene and derive the filters. Furthermore, the proposed method is implemented on an FPGA, and favorable image synthesis has been achieved in real time.

DOI： 10.1109/ISPACS.2009.5383824

Web of Science

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

We have studied arbitrary viewpoint image synthesis using multiple sensors based on image-based rendering, in which the depth estimation is required for generating precise virtual images. Major problems in this estimation process include the increase of computational efforts and the decrease in performance for occluded regions. To solve these difficulties, we improve our depth estimation process by using the multi-resolution method and by weighting similar pixels to the target pixel in the block matching. Furthermore, we incorporate the proposed method to our prototype hardware system using the CMOS image sensors we have originally developed. Experimental results show that our proposed method and prototype system are efficient and effective compared to the previous work and that arbitrary viewpoint images are synthesized favorably. Copyright © 2009 by the Association for Computing Machinery, Inc.

DOI： 10.1145/1670252.1670301

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：電子情報通信学会  

筆者らは,焦点合せの異なる画像群に線形の三次元フィルタを施すことで様々な画像を生成する手法を検討している.ここでは,演算量の大きな三次元FFTにかえて,次元削減と二次元FFTに基づき効率的に所望の自由視点画像を生成する手法を示す.

CiNii Books

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

This paper deals with the technique for generating free viewpoint images by using multi-focus imaging sequences. The method may enable us to realize dense 4-D ray-space reconstruction from 3-D multi-focus imaging sequences. Previously, we proposed a method of generating free viewpoint, iris and focus images directly from multi-focus imaging sequences with a 3-D convolution filter that expresses how the scene is defocused in the sequence. However, the cost of the spatial frequency analysis based on 3-D FFT is not inexpensive. In this paper, efficient reconstruction of free viewpoint images by dimension reduction and 2-D FFT is discussed. We show some experimental results by using synthetic and real images. Epipolar plane images are also reconstructed in order to show the disparity between generated free viewpoint images clearly. © 2008 SPIE-IS&amp
T.

DOI： 10.1117/12.767604

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Massey Univ. (New Zieland)  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：電子情報通信学会  

円形に配置された多眼カメラの取得画像群から,中心視点画像を生成するため手法を提案する.シーンを含む奥行範囲からの取得光線の値をすべて加算した画像から中心視点画像を生成するための逆フィルタを二次元周波数領域で導出する.

CiNii Books

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：電子情報通信学会  

本論文では,焦点合せの異なる画像群からの全焦点画像の生成について論ずる.筆者らが提案してきた三次元FFTに基づく手法は演算コスト等が小さくない.画像群を統合した単一画像への二次元フィルタの適用により高速,安定に画像生成を実現する手法を示す.

CiNii Books

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：電子情報通信学会  

2層の奥行からなるシーンに対して,正方形の頂点に配置された4眼カメラの取得画像群から,中心視点画像を直接生成するための,線形かつシフト不変なフィルタを導出する.従来のLight Field Rendering法では,劣化が生じる条件であっても,提案フィルタにより,領域分割を行うことなく,中心視点画像を鮮鋭に生成できる.

CiNii Books

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

This paper deals with all-in-focus image reconstruction by merging multiple differently focused images. We previously proposed a method of generating an all-in-focus image from multi-focus imaging sequences based on a 3-D filtering. In this paper, we first combine the sequence into a 2-D image. Just by applying a 2-D filter to the image, we realize fast reconstruction of all-in-focus images robustly. In order to reduce the cost of image acquisition, the optimal number of multiple differently focused images is also discussed. In addition, we introduce a simple estimation method utilizing the 2-D filter for the parameter of 3-D blurs. We show experimental results of fast all-in-focus image reconstruction by using synthetic and real images. © 2007 IEEE.

DOI： 10.1109/ICASSP.2007.366021

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPIE-INT SOC OPTICAL ENGINEERING  

This paper deals with a view interpolation problem using multiple images captured with a circular camera array. An inverse filtering method for reconstructing a virtual image at the center of the camera array is proposed. First, we generate a candidate image by adding all correspondence pixel values based on multiple layers assumed in a scene. Second, we model a linear relationship between the desired virtual image and the candidate image, and then derive the inverse filter to reconstruct the virtual image. Since we can derive the inverse filter independent of the scene structure, the proposed method requires no depth estimation. Simulation results using synthetic images show that increasing the number of cameras and layers improves the quality of the virtual image.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

This paper deals with a view interpolation problem using multiple images captured with a circular camera array. A novel deconvolution method for reconstructing a virtual image at the center of the camera array is presented and discussed in a framework of image restoration in the frequency domain. The reconstruction filter does not depend on the scene structure
therefore the presented method requires no depth estimation. The simulation result using synthetic images shows that increasing the number of the cameras improves the quality of the virtual image. ©2006 IEEE.

DOI： 10.1109/ICIP.2006.312735

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

This paper describes a method of scene re-focusing with various iris shapes by integrating a sequence of multiple differently focused images. First, we introduce a formula that combines the sequence and spatial information of a scene with a convolution of a 3-D blur. The blur expresses how the scene is defocused in the sequence. Based on the formula, in the 3-D frequency domain we can design filters merging certain frequency components of the sequence to generate images that would be acquired with various iris shapes. Some experiments of scene re-focusing using synthetic and real images indicate that we can not only arbitrarily suppress blurs of the sequence but also generate images with asymmetrical blurs like motion blurs. ©2006 IEEE.

DOI： 10.1109/ICIP.2006.312846

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：電子情報通信学会  

Light field rendering (LFR)とは, あらかじめ取得された多視点画像から自由視点画像を合成する, イメージベーストレンダリングの基本的な手法である.この手法では, 合成画像において焦点ぼけのような現象が現れることが知られている.現実のシステムでは, この"焦点"が合う範囲が非常に狭い場合が多いという問題点がある.本論文では, LFRの合成画像における"合焦"の度合を, 安定に判定する新しい尺度を提案する.また, この尺度を用いて, "合焦"距離が異なる多数枚の画像から, "焦点"が合っている領域を統合することで, シーン全体を鮮明にとらえた"全焦点"画像を合成する手法を提案する.更に, 画像合成の実験を行い, 提案手法によって, 最終的な合成画像の品質が向上することを確認した.

CiNii Books

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

This paper describes a method of image generation based on transformation integrating multiple differently focused images. First, we assume that objects are defocused by a geometrical blurring model. And we combine acquired images on certain imaging planes and spatial frequencies of objects by using a convolution of a three-dimensional blur. Then, we reconstruct an all-in-focus image from the acquired images based on spatial frequency analysis using three-dimensional FFT. Some experiments of image generation utilizing synthesized images and real images are shown and extension of the method integrating multiple differently focused images in three-dimensional frequency domain is discussed. © Springer-Verlag Berlin Heidelberg 2005.

DOI： 10.1007/11581772_27

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）  

Image based rendering (IBR) is basically a light ray resampling method for generating a novel image without aliasing artifacts from a given set of sampled light rays. To avoid aliasing artifacts, conventional methods require an estimate of the scene geometry. In this paper, we present a novel IBR method by linear filtering without estimating the scene geometry, for the simplified case when generating a virtual image at the center of 2×2 sparse camera array for a two depth-layers scene. The reconstruction filter used in the proposed method can derived by integrating all the process in our previously proposed method into an one-shot process. © 2005 IEEE.

DOI： 10.1109/ICIP.2005.1530313

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

DOI： 10.1109/ICIP.2004.1421746

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その他リンク： https://dblp.uni-trier.de/db/conf/icip/icip2004-5.html#KubotaAC04

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：電子情報通信学会  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Eurographics  

DOI： 10.2312/EGWR/EGSR04/235-242

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その他リンク： https://dblp.uni-trier.de/db/conf/rt/rt2004.html#KubotaTAC04

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

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その他リンク： https://dblp.uni-trier.de/db/conf/icmcs/icme2004.html#KubotaAC04

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

In this paper, we present a novel approach to image-based rendering (IBR) for generating an arbitrary view image with arbitrary focus for a scene consisting two approximately constant depths. The presented method differs from the conventional IBRs using multiple view images in that we acquire two differently focused images from each camera position and render parallax and focus effects on objects at different depth simply by linear filtering of the acquired images without segmentation. Experimental results on the real images acquired with 4 cameras located in parallel are presented.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPIE-INT SOC OPTICAL ENGINEERING  

In this paper, we present a novel approach to image-based rendering (IBR) that for generates an arbitrary view image with arbitrary focus for a scene consisting two approximately constant depths. The presented method differs from the conventional IBRs using multiple view images in that we acquire two differently focused images at each camera position and render parallax and focus effects on each object simply by linear filtering of the acquired images without segmentation. Experimental results on the real images acquired with 4 cameras located in parallel are presented.

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：映像情報メディア学会  

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE COMPUTER SOC  

This paper presents a novel method to render shifting (parallax) and focussing effects on object in a scene for generating a virtual view image with arbitrary focus. Two differently focused images of a same scene-near-focused image and far-focused image-are used as input images under the assumption that a scene has near and far objects. The proposed method can freely handle the shifting and the focussing effect on each object according to the view point and the focus depth of the virtual camera only by linear filtering of the input images without any segmentation or 3D modeling of the objects. Experimental results using real images are shown to test the performance of the method.

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Inst. of Image Information and Television Engineers  

In this paper, we describe a method for generating an all-focused image from a large number of microscopic images of insects. First, we describe our previously proposed select-and-merge method for all-focused image acquisition. We can obtain good results by using this method for two differently focused images. However, this method can't give a good result when a large number of images are used. We thus developed a method that compares each image with those preceding and following it based on the estimation of focused regions. We compare the results of image reconstruction by using the new method with those obtained by using our previously method. We then generate a 3D image bye using the intensity of an all-focused image and the depth of in-focus regions, both obtained by our proposed method.

DOI： 10.3169/itej.56.263

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

This paper presents a novel method to render shifting (parallax) and focussing effects on object in a scene for generating a virtual view image with arbitrary focus. Two differently focused images of the same scene-near-focused image and far-focused image are used as input under the assumption that a scene has near and far objects. The proposed method can freely handle the shifting and the focussing effect on each object according to the view point and the focus depth of the virtual camera only by linear filtering of the input images without any segmentation or modeling of the objects. Experimental results using real images are shown to test the performance of the method.

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

DOI： 10.1109/ICIP.2001.958458

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その他リンク： https://dblp.uni-trier.de/db/conf/icip/icip2001-2.html#TsubakiKA01

記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

This paper presents a new method for detecting depth range of the scene from two differently focused images This method first generates three images with differently emphasized blui using linear filtering of the two acquired images for mole depth-sensitive estimation. In this point this method is different from the conventional approaches The discrete Fourier transform of the ratio between the generated images is then introduced as a criterion of the depth range Finally through the thresholding, process of the (11-tenon according to its correspondence to the depth oil the basis of imaging model, depth range is estimated in five steps in depth Experiments for synthesized and real images are performed to test the proposed method.

Web of Science

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：映像情報メディア学会  

本稿では, 任音焦点動画像をリアルタイムに再構成するシステムとその前処理として必要とされるレジストレーション手法の高速化を提案する.ここでは, 提案されるシステムの構成を示し, 処理の流れを説明した後, 試作システムとシミュレーション結果を示す.毎秒3フレーム程度の任意焦点動画像システムが実現できた.レジストレーション手法では, 輝度投影分布のマッチングアプローチを適用することによって, 従来の階層化マッチング法に比べて, 処理速度が200倍程度上がることが確認できた.

DOI： 10.3169/itej.54.1657

CiNii Books

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その他リンク： https://jlc.jst.go.jp/DN/JALC/00071151243?from=CiNii

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

DOI： 10.1109/ICME.2000.869598

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その他リンク： https://dblp.uni-trier.de/db/conf/icmcs/icme2000.html#AizawaKG00

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：映像情報メディア学会  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：映像情報メディア学会  

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

We propose a novel approach for producing special visual effects by fusing multiple differently focused images. This method differs from conventional image-fusion techniques because it enables us to arbitrarily generate object-based visual effects such as blurring, enhancement, and shifting. Notably, the method does not need any segmentation. Using a linear imaging model, it directly generates the desired image from multiple differently focused images.

DOI： 10.1109/76.825731

Scopus

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：IEEE  

This paper describes a novel filtering method to reconstruct an arbitrarily focused image from two differently focused images. Based on the assumption that image scene has two layers - foreground and background -, two differently focused images are used as inputs, one of which is focused on the foreground and the other is focused on the background. The linear equation that holds between these images and the desired image, which is derived from their imaging mod els, can be formulated as an image restoration problem. This paper shows that the solution of this problem exists as an inverse filter and the desired image can be reconstructed only by the linear filters. As a result, reconstruction with high accuracy and fast can be achieved. Experiments using real images are shown.

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記述言語：英語   掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：SPIE-INT SOC OPTICAL ENGINEERING  

This paper describes a novel filtering method to reconstruct an arbitrarily focused image from two differently focused images. Based on the assumption that image scene has two layers - foreground and background -, the method uses the linear imaging model of the acquired two differently focused images and the desired image with arbitrary blurring; effect manipulated independently in each Ia;ver. The linear equation that holds between these images, which is derived fi om the imaging model, can be formulated as image restoration problem. This paper shows the solution of this problem, completely exists as an inverse filter, and the desired image can be reconstructed only by the linear filtering. As a result, reconstruction with high accuracy and fast processing call be achieved. Experiments using real images are shown.

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掲載種別：研究論文（国際会議プロシーディングス）   出版者・発行元：Springer  

DOI： 10.1007/3-540-45134-X_17

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その他リンク： https://dblp.uni-trier.de/db/conf/tfcv/tfcv2000.html#AizawaKK00

記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.3169/itej.54.426

Scopus

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Inst. of Image Information and Television Engineers  

We describe an image-registration method and a camera system for multi-focus image processing. We also describe a novel method for high-speed generation of arbitrarily focused images using graphic accelerator. The registration method uses global and local registration. The former corrects for differences in the displacement and scale between acquired images by using a hierarchical block-matching technique
the latter corrects for local deformation due to lens distortion. The developed camera can capture three differently focused images simultaneously for the same scene, so that we can generate an arbitrarily focused image for dynamic scene. Finally, we show example motion images with an arbitrary focus generated from two differently focused image sequences captured by the proposed camera.

DOI： 10.3169/itej.54.260

Scopus

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記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

DOI： 10.1109/ICIP.1999.822936

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その他リンク： https://dblp.uni-trier.de/db/conf/icip/icip1999-2.html#KubotaKA99

記述言語：英語   掲載種別：研究論文（学術雑誌）   出版者・発行元：IEEE  

DOI： 10.1109/ICIP.1999.822949

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その他リンク： https://dblp.uni-trier.de/db/conf/icip/icip1999-2.html#AizawaKK99

記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：映像情報メディア学会  

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記述言語：日本語   掲載種別：研究論文（学術雑誌）   出版者・発行元：Inst. of Image Information and Television Engineers  

In this paper, we propose a novel method for generating arbitrarily focused disparity images that uses multiple differently focused images. Given the assumption that the depth of the scene changes stepwise, we derive a formula for the reconstruction between the desired arbitrarily focused disparity image and multiple acquired images
we can reconstruct the arbitrarily focused disparity image by using the formula iteratively. We show that we can reconstruct arbitrarily focused disparity images of natural scenes. Our method requires only the point spread functions of the acquired images for reconstruction, it does not require any spatial segmentation.

DOI： 10.3169/itej.52.1336

Scopus

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記述言語：英語   出版者・発行元：IEICE-INST ELECTRONICS INFORMATION COMMUNICATIONS ENG  

This paper describes a method of free iris and focus image generation based on transformation integrating multiple differently focused images. First, we assume that objects are defocused by a geometrical blurring model. And we combine acquired images on certain imaging planes and spatial information of objects by using a convolution of a three-dimensional blur. Then, based on spatial frequency analysis of the blur, we design three-dimensional filters that generate free iris and focus images from the acquired images. The method enables us to generate not only an all-in-focus image corresponding to an ideal pin-hole iris but also various images, which would be acquired with virtual irises whose sizes are different from the original one. In order to generate a certain image by using multiple differently focused images, especially very many images, conventional methods usually analyze focused regions of each acquired image independently and construct a depth map. Then, based on the map, the regions are merged into a desired image with some effects. However, generally, it is so difficult to conduct such depth estimation robustly in all regions that these methods cannot prevent merged results from including visible artifacts, which decrease the quality of generated images awfully. In this paper, we propose a method of generating desired images directly and robustly from very many differently focused images without depth estimation. Simulations of image generation are performed utilizing synthetic images to study how certain parameters of the blur and the filter affect the quality of generated images. We also introduce pre-processing that corrects the size of acquired images and a simple method for estimating the parameter of the three-dimensional blur. Finally, we show experimental results of free iris and focus image generation from real images.

DOI： 10.1093/ietisy/e90-d.1.191

Web of Science

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記述言語：英語   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

This paper presents a novel method for synthesizing a novel view from two sets of differently focused images taken by an aperture camera array for a scene consisting of two approximately constant depths. The proposed method consists of two steps. The first step is a view interpolation to reconstruct an all-in-focus dense light field of the scene. The second step is to synthesize a novel view by a light-field rendering technique from the reconstructed dense light field. The view interpolation in the first step can be achieved simply by linear filters that are designed to shift different object regions separately, without region segmentation. The proposed method can effectively create a dense array of pin-hole cameras (i.e., all-in-focus images), so that the novel view can be synthesized with better quality.

DOI： 10.1109/TIP.2006.884938

Web of Science

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記述言語：英語   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

This paper presents a novel method for synthesizing a novel view from two sets of differently focused images taken by an aperture camera array for a scene consisting of two approximately constant depths. The proposed method consists of two steps. The first step is a view interpolation to reconstruct an all-in-focus dense light field of the scene. The second step is to synthesize a novel view by a light-field rendering technique from the reconstructed dense light field. The view interpolation in the first step can be achieved simply by linear filters that are designed to shift different object regions separately, without region segmentation. The proposed method can effectively create a dense array of pin-hole cameras (i.e., all-in-focus images), so that the novel view can be synthesized with better quality.

DOI： 10.1109/TIP.2006.884938

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記述言語：英語   出版者・発行元：Institute of Electronics, Information and Communication, Engineers, IEICE  

This paper describes a method of free iris and focus image generation based on transformation integrating multiple differently focused images. First, we assume that objects are defocused by a geometrical blurring model. And we combine acquired images on certain imaging planes and spatial information of objects by using a convolution of a three-dimensional blur. Then, based on spatial frequency analysis of the blur, we design three-dimensional filters that generate free iris and focus images from the acquired images. The method enables us to generate not only an all-in-focus image corresponding to an ideal pin-hole iris but also various images, which would be acquired with virtual irises whose sizes are different from the original one. In order to generate a certain image by using multiple differently focused images, especially very many images, conventional methods usually analyze focused regions of each acquired image independently and construct a depth map. Then, based on the map, the regions are merged into a desired image with some effects. However, generally, it is so difficult to conduct such depth estimation robustly in all regions that these methods cannot prevent merged results from including visible artifacts, which decrease the quality of generated images awfully. In this paper, we propose a method of generating desired images directly and robustly from very many differently focused images without depth estimation. Simulations of image generation are performed utilizing synthetic images to study how certain parameters of the blur and the filter affect the quality of generated images. We also introduce pre-processing that corrects the size of acquired images and a simple method for estimating the parameter of the three-dimensional blur. Finally, we show experimental results of free iris and focus image generation from real images. Copyright © 2007 The Institute of Electornics, Information and Communication Engineers.

DOI： 10.1093/ietisy/e90-1.1.191

Scopus

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（その他）   出版者・発行元：日本工業出版  

CiNii Books

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記述言語：日本語  

DOI： 10.3169/itej.60.1077

Scopus

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記述言語：英語   出版者・発行元：ELSEVIER SCIENCE BV  

DOI： 10.1016/j.image.2006.03.010

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（その他）   出版者・発行元：新技術コミュニケーションズ  

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記述言語：日本語  

DOI： 10.3169/itej.60.797

Scopus

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記述言語：日本語   出版者・発行元：一般社団法人電子情報通信学会  

筆者らは, 焦点合わせの異なる多数枚の撮像画像群を3次元情報とみなし, これから様々な映像を生成する手法を検討している.本稿ではまず, 撮像画像間の撮像範囲の相違や焦点合わせ間隔の補正等により, 焦点ぼけ画像群を適切に構造化する手法を検討する.あわせて, 構造化後の3次元焦点ぼけを表すパラメータと生成画像の品質との関係を雑音への耐性も含めて検証し, 望ましい撮像条件を明らかにする.また, 画像生成時に仮定したぼけの程度や対象物体の存在範囲などからの誤差の影響による品質劣化についても検証を行い, 本手法が有効に機能する範囲を示すとともに, 窓関数を用いた劣化抑制等の必要性の有無など一般の劣化画像の復元処理との相違についても論ずる.

CiNii Books

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記述言語：日本語   出版者・発行元：一般社団法人情報処理学会  

筆者らは，焦点合わせの異なる多数枚の撮像画像群を3次元情報とみなし，これから様々な映像を生成する手法を検討している．本稿ではまず，撮像画像間の撮像範囲の相違や焦点合わせ間隔の補正等により，焦点ぼけ画像群を適切に構造化する手法を検討する．あわせて，構造化後の3次元焦点ぼけを表すパラメータと生成画像の品質との関係を雑音への耐性も含めて検証し，望ましい撮像条件を明らかにする．また，画像生成時に仮定したぼけの程度や対象物体の存在範囲などからの誤差の影響による品質劣化についても検証を行い，本手法が有効に機能する範囲を示すとともに，窓関数を用いた劣化抑制等の必要性の有無など一般の劣化画像の復元処理との相違についても論ずる．This paper deals with image generation based on transformation integrating multiple differently focused images into structured 3-D information. First, we describes a method of image size correction and focus interpolation for the integration. In addition, relation between a certain parameter of the structured 3-D information and quality of generated images is discussed taking noise into consideration. Furthermore, we examine how errors of assumptions about blurs and scenes degrade generated images. Difference between our proposed method and conventional image restoration such as necessity of using window functions is also mentioned.

CiNii Books

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その他リンク： http://id.nii.ac.jp/1001/00041160/

記述言語：日本語   出版者・発行元：映像情報メディア学会  

CiNii Books

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記述言語：英語   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

We present a novel filtering method for reconstructing an all-in-focus image or an arbitrarily focused image from two images that are focused differently. The method can arbitrarily manipulate the degree of blur of the objects using linear filters without segmentation. The filters are uniquely determined from a linear imaging model in the Fourier domain. An effective and accurate blur estimation method is developed. The simulation results show that the accuracy and computational time of the proposed method are improved compared with the previous iterative method and that the effects of blur estimation error on the quality of the reconstructed image are very small. The method performs well for real images acquired without visible artifacts.

DOI： 10.1109/TIP.2005.854468

Web of Science

PubMed

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記述言語：英語   出版者・発行元：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

We present a novel filtering method for reconstructing an all-in-focus image or an arbitrarily focused image from two images that are focused differently. The method can arbitrarily manipulate the degree of blur of the objects using linear filters without segmentation. The filters are uniquely determined from a linear imaging model in the Fourier domain. An effective and accurate blur estimation method is developed. The simulation results show that the accuracy and computational time of the proposed method are improved compared with the previous iterative method and that the effects of blur estimation error on the quality of the reconstructed image are very small. The method performs well for real images acquired without visible artifacts.

DOI： 10.1109/TIP.2005.854468

Web of Science

PubMed

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記述言語：日本語   掲載種別：記事・総説・解説・論説等（その他）   出版者・発行元：日本工業出版  

CiNii Books

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記述言語：日本語   出版者・発行元：電子情報通信学会  

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記述言語：日本語   会議種別：口頭発表（一般）  

researchmap

記述言語：日本語   会議種別：口頭発表（一般）  

researchmap

記述言語：日本語   会議種別：口頭発表（一般）  

researchmap

記述言語：日本語   会議種別：口頭発表（一般）  

researchmap

記述言語：日本語   会議種別：口頭発表（一般）  

researchmap