Publishing type：Research paper (scientific journal)   Publisher：Institute of Electronics, Information and Communications Engineers (IEICE)  

DOI： 10.1587/transinf.2019pcp0006

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：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

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：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.

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Authorship：Lead author  

DOI： 10.14923/transinfj.2015JDP7025

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：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.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：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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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Institute of Image Electronics Engineers of Japan  

In this paper, we propose a novel multi-encoding method for high efficiency intra-frame coding using multiple hybrid coders that combine non-causal interpolative prediction and orthogonal transforms. For hybrid coders, we set 11 different coding modes that employ different orthogonal transforms and the quantization scan orders. For each 8×8 block, computing in parallel the coding errors of all the coding modes, we adaptively select the best mode that gives the minimum error and then send their quantization information with the selected mode number as the overhead information. The simulation results using the standard test images showed that compared to H.264 (with high complexity mode) the proposed method performs better in the higher coding rate and improves PSNR by 6 dB at most.

DOI： 10.11371/iieej.42.345

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：画像電子学会  

This paper presents a novel hybrid image coding method that combines interpolative prediction and orthogonal transform to achieve higher compression rate. In 8×8 block-wise manner, the presented method first predicts pixel values using the neighboring pixel values including non-causal ones and transforms the obtained error values into coefficients through discrete cosine transform (DCT). The obtained DCT coefficients are quantized by the feedback quantization scheme so that the coding error power is suppressed when decoded. In the quantization, for further higher compression rate, the presented method switches the quantization order into inverse zigzag scan from zigzag scan and controls the quantization step according to the precomputed coefficient that is the gain of the coding error power. Simulation results show that the proposed method gains higher compression rate by 2.0dB than the conventional method using the interpolative quantization only.

DOI： 10.11371/iieej.40.985

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Language：English   Publishing type：Research paper (scientific journal)  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Institute of Image Information and Television Engineers  

We propose a method of virtual bokeh reconstruction by using only multiple differently-focused images acquired with a single system of lenses. First, we analyzed our previously proposed 3-D blurring filter that combines scene information and the acquired multiple differently-focused images to decompose the filter into ray-sets, each of which goes through a certain point on the lens. A new 2-D filter based on dimension reduction was then designed to allow the ray-sets to be reconstructed without the need to estimate the scene. A weighted composition of them provides free shapes of bokeh, i.e., the desired features of lenses and irises. Virtual bokeh reconstruction was simulated by utilizing synthetic multiple differently-focused images with a number of shapes of bokeh. The criteria for appropriate bokeh for image acquisition were also clarified. Finally, we show experimental results of virtual bokeh reconstruction from real images.

DOI： 10.3169/itej.65.372

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：画像電子学会  

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Language：English   Publishing type：Research paper (international conference proceedings)  

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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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：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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Other Link： https://jlc.jst.go.jp/DN/JALC/00340281879?from=CiNii

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：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

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Language：English   Publishing type：Research paper (international conference proceedings)  

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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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：電子情報通信学会  

CiNii Books

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Language：English   Publishing type：Research paper (international conference proceedings)  

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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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Massey Univ. (New Zieland)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：電子情報通信学会  

CiNii Books

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：電子情報通信学会  

CiNii Books

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：電子情報通信学会  

CiNii Books

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Language：English   Publishing type：Research paper (international conference proceedings)  

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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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：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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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

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Language：English   Publishing type：Research paper (international conference proceedings)  

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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Language：English   Publishing type：Research paper (international conference proceedings)  

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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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：電子情報通信学会  

CiNii Books

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Language：English   Publishing type：Research paper (international conference proceedings)  

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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Language：English   Publishing type：Research paper (international conference proceedings)  

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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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

DOI： 10.1109/ICIP.2004.1421746

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Other Link： https://dblp.uni-trier.de/db/conf/icip/icip2004-5.html#KubotaAC04

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：電子情報通信学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Eurographics  

DOI： 10.2312/EGWR/EGSR04/235-242

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Other Link： https://dblp.uni-trier.de/db/conf/rt/rt2004.html#KubotaTAC04

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

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Other Link： https://dblp.uni-trier.de/db/conf/icmcs/icme2004.html#KubotaAC04

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：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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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：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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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：映像情報メディア学会  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：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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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：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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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：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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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

DOI： 10.1109/ICIP.2001.958458

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Other Link： https://dblp.uni-trier.de/db/conf/icip/icip2001-2.html#TsubakiKA01

Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：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.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：映像情報メディア学会  

DOI： 10.3169/itej.54.1657

CiNii Books

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Other Link： https://jlc.jst.go.jp/DN/JALC/00071151243?from=CiNii

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

DOI： 10.1109/ICME.2000.869598

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Other Link： https://dblp.uni-trier.de/db/conf/icmcs/icme2000.html#AizawaKG00

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：映像情報メディア学会  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：映像情報メディア学会  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：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

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：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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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：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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Publishing type：Research paper (international conference proceedings)   Publisher：Springer  

DOI： 10.1007/3-540-45134-X_17

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Other Link： https://dblp.uni-trier.de/db/conf/tfcv/tfcv2000.html#AizawaKK00

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.3169/itej.54.426

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：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

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

DOI： 10.1109/ICIP.1999.822936

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Other Link： https://dblp.uni-trier.de/db/conf/icip/icip1999-2.html#KubotaKA99

Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE  

DOI： 10.1109/ICIP.1999.822949

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Other Link： https://dblp.uni-trier.de/db/conf/icip/icip1999-2.html#AizawaKK99

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：映像情報メディア学会  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：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

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Language：English   Publisher：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

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Language：English   Publisher：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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Language：English   Publisher：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

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (other)   Publisher：日本工業出版  

CiNii Books

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Language：Japanese  

A method for generating all-in-focus images by integrating multiple differently focused images is described. First, based on the assumption that objects are defocused by a simple geometrical blurring model, we derive a formula between acquired images on certain imaging planes and spatial information of objects by using a convolution of a 3-D blur. Then, we analyze spatial frequency components of the blur kernel to obtain a 3-D filter that generates an all-in-focus image from the acquired images. Simulations of image generation are performed utilizing synthetic images to study how noise, object depths, and certain parameters of the blur and the filter affect the quality. We also introduce pre-processing that corrects the size of acquired images and a simple method for estimating the parameter of the 3-D blur. Finally, we show experimental results of all-in-focus image generation from real images.

DOI： 10.3169/itej.60.1077

Scopus

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Language：English   Publisher：ELSEVIER SCIENCE BV  

DOI： 10.1016/j.image.2006.03.010

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (other)   Publisher：新技術コミュニケーションズ  

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Language：Japanese  

This paper presents a novel method for synthesizing a virtual view from two sets of differently focused images taken by an aperture camera array for a scene 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 virtual view from the reconstructed dense light field by using light field rendering technique. The view interpolation in the first step can be achieved simply with linear filters that are designed to shift different object regions separately without estimating the depth map of the scene. The proposed method can effectively create a dense array of pin-hole cameras (i.e., all-focused images) so that the virtual view can be synthesized with higher quality.

DOI： 10.3169/itej.60.797

Scopus

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Language：Japanese   Publisher：The Institute of Electronics, Information and Communication Engineers  

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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Language：Japanese   Publisher：Information Processing Society of Japan (IPSJ)  

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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Other Link： http://id.nii.ac.jp/1001/00041160/

Language：Japanese  

CiNii Books

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Language：English   Publisher：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

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PubMed

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (other)   Publisher：日本工業出版  

CiNii Books

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Language：Japanese   Publisher：電子情報通信学会  

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