• Title, Summary, Keyword: Image reconstruction

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Simulation Study for Feature Identification of Dynamic Medical Image Reconstruction Technique Based on Singular Value Decomposition (특이값분해 기반 동적의료영상 재구성기법의 특징 파악을 위한 시뮬레이션 연구)

  • Kim, Do-Hui;Jung, YoungJin
    • Journal of radiological science and technology
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    • v.42 no.2
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    • pp.119-130
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    • 2019
  • Positron emission tomography (PET) is widely used imaging modality for effective and accurate functional testing and medical diagnosis using radioactive isotopes. However, PET has difficulties in acquiring images with high image quality due to constraints such as the amount of radioactive isotopes injected into the patient, the detection time, the characteristics of the detector, and the patient's motion. In order to overcome this problem, we have succeeded to improve the image quality by using the dynamic image reconstruction method based on singular value decomposition. However, there is still some question about the characteristics of the proposed technique. In this study, the characteristics of reconstruction method based on singular value decomposition was estimated over computational simulation. As a result, we confirmed that the singular value decomposition based reconstruction technique distinguishes the images well when the signal - to - noise ratio of the input image is more than 20 decibels and the feature vector angle is more than 60 degrees. In addition, the proposed methode to estimate the characteristics of reconstruction technique can be applied to other spatio-temporal feature based dynamic image reconstruction techniques. The deduced conclusion of this study can be useful guideline to apply medical image into SVD based dynamic image reconstruction technique to improve the accuracy of medical diagnosis.

The Analysis of Resolution on the Image Reconstnlction Algorithms for Ultrasonic Diffraction Tomography (초음파 회절 토모그라피 영상복원 알고리즘의 분해능 분석)

  • 구길모;황기환
    • The Journal of the Acoustical Society of Korea
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    • v.18 no.5
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    • pp.83-90
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    • 1999
  • In this paper, we studied resolution to the FBP and BFP image reconstruction algorithms for ultrasonic diffraction tomography. In order to analyze the resolution to the tomographic images which can be reconstructed from the modified FBP image reconstruction algorithm by using fixed coordinate system and BFP image reconstruction algorithm which is suitable for plane structure object, we derived ambiguity functions to these algorithms and then analyzed lateral and depth resolution through simulation respectively. Simulation results show that the lateral and depth resolution to the FBP image reconstruction algorithm and the BFP image reconstruction algorithm was determined 0.27 λ, 0.70 λ and 0.39 λ, 0.98 λ at the 3dB respectively. These results imply that modified FBP and BFP image reconstruction algorithms for diffraction tomography is useful in the tomographic image reconstruction.

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3D FACE RECONSTRUCTION FROM ROTATIONAL MOTION

  • Sugaya, Yoshiko;Ando, Shingo;Suzuki, Akira;Koike, Hideki
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • pp.714-718
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    • 2009
  • 3D reconstruction of a human face from an image sequence remains an important problem in computer vision. We propose a method, based on a factorization algorithm, that reconstructs a 3D face model from short image sequences exhibiting rotational motion. Factorization algorithms can recover structure and motion simultaneously from one image sequence, but they usually require that all feature points be well tracked. Under rotational motion, however, feature tracking often fails due to occlusion and frame out of features. Additionally, the paucity of images may make feature tracking more difficult or decrease reconstruction accuracy. The proposed 3D reconstruction approach can handle short image sequences exhibiting rotational motion wherein feature points are likely to be missing. We implement the proposal as a reconstruction method; it employs image sequence division and a feature tracking method that uses Active Appearance Models to avoid the failure of feature tracking. Experiments conducted on an image sequence of a human face demonstrate the effectiveness of the proposed method.

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Analysis of Image Quality and Optimized Reconstruction Window through Heart Rate and Its Variation in Retrospectively ECG-gated Coronary Angiography Using Multi-Detector Row CT

  • Lee, Sang-Ho;Park, Byoung-Wook;Kim, Hee-Joung;Haijo Jung;Kang, Won-suk;Son, Hye-Kyung;Choe, Kyu-Ok
    • Proceedings of the Korean Society of Medical Physics Conference
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    • pp.461-463
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    • 2002
  • Image quality and selection of optimized window for good quality reconstruction in coronary angiography using multi-detector row CT (MDCT) have not been studied by heart rate and its variation. Therefore, the effect of heart rate and its variation was systemically analyzed. Eighty-three patients were undergone contrast-enhanced coronary angiography using MDCT. In this study, sixty cases were enrolled. Two radiologists graded image quality as follows: 4, excellent; 3, good; 2, fair; l, bad. The starting points of the reconstruction window were chosen at seventy and forty percent of R wave interval. Optimized window was scored as 1 when 40% reconstruction was better quality than 70%, as 2 when 40% reconstruction is same as 70%, and as 3 when 70% reconstruction was better than 40%. Regression analysis was performed. The range of variation of beats per minute (BPM) was well correlated with image quality (r=-0.55, p=0.000), however correlation with optimized window percentage was not statistically significant (p=0.969). By contraries, median value of BPM was comparatively well correlated with optimized window grade (r=-0.24, p=0.086). Median value of BPM was not well correlated with image quality (r=0.l70, p=0.l97). Image quality is more affected by variation of heart rate (VHR) than by higher heart rate. Selection of optimized reconstruction window for good image quality is mainly affected by heart rate and there is a tendency that systolic phase reconstruction is better in image quality than diastolic reconstruction in higher heart rate.

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SUPER RESOLUTION RECONSTRUCTION FROM IMAGE SEQUENCE

  • Park Jae-Min;Kim Byung-Guk
    • Proceedings of the KSRS Conference
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    • pp.197-200
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    • 2005
  • Super resolution image reconstruction method refers to image processing algorithms that produce a high resolution(HR) image from observed several low resolution(LR) images of the same scene. This method is proved to be useful in many practical cases where multiple frames of the same scene can be obtained, such as satellite imaging, video surveillance, video enhancement and restoration, digital mosaicking, and medical imaging. In this paper we applied super resolution reconstruction method in spatial domain to video sequences. Test images are adjacently sampled images from continuous video sequences and overlapped for high rate. We constructed the observation model between the HR images and LR images applied by the Maximum A Posteriori(MAP) reconstruction method that is one of the major methods in the super resolution grid construction. Based on this method, we reconstructed high resolution images from low resolution images and compared the results with those from other known interpolation methods.

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FREE VIEWPOINT IMAGE RECONSTRUCTION FROM 3-D MULTI-FOCUS IMAGING SEQUENCES AND ITS IMPLEMENTATION BY CELL-BASED COMPUTING

  • Yonezawayz, Hiroki;Kodamay, Kazuya;Hamamotoz, Takayuki
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • pp.751-754
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    • 2009
  • This paper deals with the Cell-based distributed processing for generating free viewpoint images by merging multiple differently focused images. We previously proposed the method of generating free viewpoint images without any depth estimation. However, it is not so easy to realize real-time image reconstruction based on our previous method. In this paper, we discuss the method to reduce the processing time by dimension reduction for image filtering and Cell-based distributed processing. Especially, the method of high-speed image reconstruction by the Cell processor on SONY PLAYSTATION3(PS3) is described in detail. We show some experimental results by using real images and we discuss the possibility of real-time free viewpoint image reconstruction.

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Reconstruction of Wide FOV Image from Hyperbolic Cylinder Mirror Camera (실린더형 쌍곡면 반사체 카메라 광각영상 복원)

  • Kim, Soon-Cheol;Yi, Soo-Yeong
    • The Journal of Korea Robotics Society
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    • v.10 no.3
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    • pp.146-153
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    • 2015
  • In order to contain as much information as possible in a single image, a wide FOV(Field-Of-View) imaging system is required. The catadioptric imaging system with hyperbolic cylinder mirror can acquire over 180 degree horizontal FOV realtime panorama image by using a conventional camera. Because the hyperbolic cylinder mirror has a curved surface in horizontal axis, the original image acquired from the imaging system has the geometrical distortion, which requires the image processing algorithm for reconstruction. In this paper, the image reconstruction algorithms for two cases are studied: (1) to obtain an image with uniform angular resolution and (2) to obtain horizontally rectilinear image. The image acquisition model of the hyperbolic cylinder mirror imaging system is analyzed by the geometrical optics and the image reconstruction algorithms are proposed based on the image acquisition model. To show the validity of the proposed algorithms, experiments are carried out and presented in this paper. The experimental results show that the reconstructed images have a uniform angular resolution and a rectilinear form in horizontal axis, which are natural to human.

Image Reconstruction Techniques for Radioactive Waste Assay by Tomographic Gamma Scanning Method

  • Zhang Quanhu;Kim Ki-Hong;Hong Kwon-Pyo
    • Proceedings of the Korean Radioactive Waste Society Conference
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    • pp.126-140
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    • 2005
  • The tomographic gamma scanner (TGS) method, a further of extension of segmented gamma scanner (SGS), is most accurate and precise for assaying heterogeneous drummed nuclear radioactive waste; it is widely used in nuclear power plants and radioactive waste storages and disposal sites. The transmission and emission images are reconstructed by image reconstruction techniques. In the paper, the principle of TGS is introduced; image reconstruction techniques are discussed as well; finally, it is demonstrated that TGS method performance.

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A Study on Speed Improvement of Medical Image Reconstruction Using Limited Range Process (부분영역처리를 이용한 영상재구성의 속도개선에 관한 연구)

  • Ryu, Jong-Hyun;Beack, Seung-Hwa
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.5
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    • pp.658-663
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    • 1999
  • 2D sliced CT images hardly express the human disease in a space. This space expression can be reconstructed into 3D image by piling up the CT sliced image in succession. In medical image, in order to get the reconstructed 3D images, expensive system or much calculation time is needed. But by changing the method of reconstruction procedure and limit the range, the reconstruction time could be reduced. In this study, to reduce the processing time and memory, we suggested a method of interpolation and ray casting processing at the same time in a limited range. Such a limited range processing have advantages that we could reduce the unnecessary interpolation and ray casting. Through a experiment, it is founded that the reconstruction time and the memory was much reduced.

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Image Reconstruction Using 2D M-ch Perfect Reconstruction Filter Bank with Optimized Adaptive interpolation kernel (최적 적응 보간 커널 기반 2차원 M-채널 완전 복원 Filter Bank를 이용한 이미지 재구성)

  • Kim, Jin-Young;Nam, Sang-Won
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.4
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    • pp.795-798
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    • 2007
  • In this paper, we propose an image reconstruction method utilizing an optimized adaptive interpolation kernel along with a 2D M-channel perfect reconstruction filter bank (M-ch PR-FB) structure. In particular, the proposed approach leads to construction of a sharper image than a direct conversion, still preserving high frequency components of the original image through the subband processing of the 2D M-ch PR-FB. Finally, the image quality of the proposed approach is demonstrated by comparing with those of the direct methods using conventional interpolation kernels.