• Title/Summary/Keyword: Reconstructed image

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A study of Image Compression Algorithm using DCT (DCT를 이용한 영상압축 알고리즘에 관한 연구)

  • 한동호;이준노
    • Journal of Biomedical Engineering Research
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    • v.13 no.4
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    • pp.323-330
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    • 1992
  • A Study of Image Compression Algorithm using DCT This paper describes the system that implement a JPEG(Joint Photographic Experts Group) algorithm based on DCT(Discrete Cosine Transform) uslng CCD kameva, Image Grabber, and IBM PC. After cosine transforms the acquisited image, this algorithm quantize and entropy encode the coefficients by JPEG code table. The coefficients are reconstructed by the Huffman decoding, dequantized procedure, and Inverse cosine transform. The results obtained from the impleulented system are as follows. (1) For effcient storage and easy implementation, this system save Image as a PCX formal (2) Thls system get 7:1 compression ratio(3.8 RMSE value) without large distortion. (3) With a low pass filtering, thls system eliminate high frequency components and get 20% enhanced compression ratio. (4) Thls system enhance the reconstructed Image using histogram modeling.

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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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Inverse halftoning Using Anisotropic diffusion and Edge map (비등방성 확산 필터와 에지맵을 이용한 역하프토닝)

  • 고기영;주동현;염동훈;김두영
    • Proceedings of the Korea Institute of Convergence Signal Processing
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    • 2000.12a
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    • pp.81-84
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    • 2000
  • Digital Halftoning convert a continuous-tone images to a binary images. Inverse halftoning addresses the problem of recovering a continuous image from a halftoned binary image. Simple low pass filtering can remove the high frequency noise but it also removes the edge information. Thus the edge information should be separated from the halftoning noise. As a result, the edge of result image is blurring. This paper present that we obtain continuous-tone-image which using Anisotropic diffusion filter. To reduce noise without blurring the edges of reconstructed image use edge map. The experimental results show that proposed method gives a higher PSNR and better subjective quality than conventional methods. As a result, the edge information of reconstructed image reduce blurring.

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Transducer Combination for High-Quality Ultrasound Tomography Based on Speed of Sound Imaging (속도 분포 기반 단층촬영을 위한 최적의 트랜스듀서의 조합)

  • Kim, Young Hun;Park, Kwan Kyu
    • Journal of the Korean Society for Nondestructive Testing
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    • v.36 no.1
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    • pp.27-34
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    • 2016
  • The type of ultrasound transducer used influences the quality of a reconstructed ultrasound image. This study analyzed the effect of transducer type on ultrasound computed tomography (UCT) image quality. The UCT was modeled in an ultrasound simulator by using a 5 cm anatomy model and a ring-shape 5 MHz 128 transducer array, which considered attenuation, refraction, and reflection. Speed-of-sound images were reconstructed by the Radon transform as the UCT image modality. Acoustic impedance images were also reconstructed by the delay-and-sum (DAS) method, which considered the speed of sound information. To determine the optimal combination of transducers in observation, point-source, flat, and focused transducers were tested in combination as trasmitters and receivers; UCT images were constructed from each combination. The combination of point-source/flat transducer as transmitting and receiving devices presented the best reconstructed image quality. In UCT implementation, the combination of a flat transducer for transmitting and a point transducer for receiving permitted acceptable image quality.

Iterative Fourier Transform Algorithm Based on the Segmentation of Target Image for a High-Speed Binary Spatial Light Modulator

  • Im, Yeonsu;Kim, Hwi;Hahn, Joonku
    • Journal of the Optical Society of Korea
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    • v.19 no.2
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    • pp.149-153
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    • 2015
  • A digital micro-mirror device (DMD) has the potential to modulate an incident wave with high speed, and the application for holographic display has been studied by many researchers. However, the quality of reconstructed image isn't good in comparison with that from a gray-scale amplitude-only hologram since it is a binary amplitude-only spatial light modulator (SLM). In this paper, we suggest a method generating a set of binary holograms to improve the quality of the reconstructed image. Here, we are concerned with the case for which the object plane is positioned at the Fourier domain of the plane of the SLM. In this case, any point in the Fourier plane is related to all points in the hologram. So there is a chance to generate a set of binary holograms illuminated by incident wave with constant optical power. Moreover, we find an interesting fact that the quality of reconstructed image is improved when the spatial frequency bandwidth of the binary hologram is limited. Therefore, we propose an iterative segmentation algorithm generating a set of binary holograms that are designed to be illuminated by the wave with constant optical power. The feasibility of our method is experimentally confirmed with a DMD.

Accurate lattice extraction of elemental image array and pre-processing methods in computational integral imaging (컴퓨터 집적 영상에서의 정교한 요소 영상 추출 및 전처리 방법)

  • Son, Jeong-Min;Yoo, Hoon
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.5
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    • pp.1164-1170
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    • 2011
  • In this paper, we propose accurate lattice extraction of elemental image array and pre-processing methods in computational integral imaging. Pre-processing methods remove distortions and noises of the image. Such distortions occurred in pickup systems are rotational errors. Distortions will degrade the resolution of reconstructed images. To overcome this problem, we propose our methods for extraction of elemental image array and pre-processing methods. Also, we describe that distortions affect the high quality reconstruction. Optical and computational experiments indicate that reconstructed images applied our methods is better than reconstructed images unapplied our methods.

Analysis of Quantization Error in Stereo Vision (스테레오 비젼의 양자화 오차분석)

  • 김동현;박래홍
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.30B no.9
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    • pp.54-63
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    • 1993
  • Quantization error, generated by the quantization process of an image, is inherent in computer vision. Because, especially in stereo vision, the quantization error in a 2-D image results in position errors in the reconstructed 3-D scene, it is necessary to analyze it mathematically. In this paper, the analysis of the probability density function (pdf) of quantization error for a line-based stereo matching scheme is presented. We show that the theoretical pdf of quantization error in the reconstructed 3-D position information has more general form than the conventional analysis for pixel-based stereo matching schemes. Computer simulation is observed to surpport the theoretical distribution.

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An Edge-detecting Bayesian Image Reconstruction for Positron Emission Tomography

  • Um, Jong-Seok;Choi, Byong-Su
    • Communications for Statistical Applications and Methods
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    • v.4 no.3
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    • pp.817-825
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    • 1997
  • Images reconstructed with EM algorithm have been observed to have checkerboard effects and have large distortions near edges as iterations proceed. We suggest a aimple algorithm of applying line process to the EM and Bayesian EM to reduce the distortions near edges. We show by simulation that this algorithm improves the clarity of the reconstructed image and has good properties based on root mean square error.

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Image Downsizing and Upsizing Scheme in the Compressed Domain Using Modified IDCT (변경된 IDCT를 이용한 압축 영역에서의 영상 축소 및 확대 기법)

  • 서성주;이명희;오상욱;설상훈
    • Journal of Broadcast Engineering
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    • v.8 no.1
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    • pp.30-36
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    • 2003
  • According to an evolution of image and video compression technologies, most digital images are in the compressed form. Resizing of these compressed images have various applications such as transmission of resized image according to varying bandwidth, content adaptation for display purpose and etc. Discrete Cosine Transform (DCT) is the most popular transformation for image compression. Recently, several researches have been performed to obtain the reconstructed image of original size in the DCT domain after downsampling and upsampling in the DCT domain. Main focus of these researches is to improve quality of the reconstructed image after downsampling and upsampling in the DCT domain In this paper, we present an modified IDCT method to downsize DCT-encoded image. Furthermore, we propose an efficient scheme for image downsampling and upsampling in the DCT domain With these modified IDCT method. The proposed scheme Provides higher PSNR values than the existing schemes In terms of the reconstructed image after halving and doubling in the DCT domain.

Metal Area Segmentation in X-ray CT Images Using the RNA (Relevant Neighbor Ar ea) Principle

  • Kim, Youngshin;Kwon, Hyukjoon;Kim, Joongkyu;Yi, Juneho
    • Journal of Korea Multimedia Society
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    • v.15 no.12
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    • pp.1442-1448
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    • 2012
  • The problem of Metal Area Segmentation (MAS) in X-ray CT images is a very hard task because of metal artifacts. This research features a practical yet effective method for MAS in X-ray CT images that exploits both projection image and reconstructed image spaces. We employ the Relevant Neighbor Area (RNA) idea [1] originally developed for projection image inpainting in order to create a novel feature in the projection image space that distinctively represents metal and near-metal pixels with opposite signs. In the reconstructed result of the feature image, application of a simple thresholding technique provides accurate segmentation of metal areas due to nice separation of near-metal areas from metal areas in its histogram.