• Journal of the Chungcheong Mathematical Society
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• v.33 no.4
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• pp.505-516
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• 2020

This study shows that image deblurring problems can be transformed into the multi-parameter Tikhonov type with multiple right hand sides. Also, this paper proposes the extension of the global generalized cross validation to obtain an appropriate choice of the regularization parameters for this problem. The experimental results of using the preconditioned Gl-CGLS algorithm were analyzed.

• Journal of Broadcast Engineering
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• v.23 no.4
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• pp.484-494
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• 2018

The uniform motion blur removing algorithm of Cho et al. has the problem that the edge region of the image cannot be restored clearly. We propose the effective algorithm to overcome this problem by using shock filter that reconstructs a blurred step signal into a sharp edge, and convolutional neural network (CNN) that learns by extracting features from the image. Then uniform motion blur kernel is estimated from the latent sharp image to remove blur in the image. The proposed algorithm improved the disadvantages of the conventional algorithm by reconstructing the latent sharp image using shock filter and CNN. Through the experimental results, it was confirmed that the proposed algorithm shows excellent reconstruction performance in objective and subjective image quality than the conventional algorithm.

• The KIPS Transactions:PartA
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• v.13A no.5 s.102
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• pp.429-434
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• 2006

A CCTV system reduces some number of cameras if we use convex-mirror. In this case, convex-mirror Image distorted, we need transformation to flat images. In the center of mirror images, a transformed image has no distortion, but at near boundary image has plentiful distortion. This distortion is caused by occlusion of angled ray and diffraction. We know that the linear filtering approach cannot separate noise from signal where their Fourier spectra overlap. But using a non-linear discretization method, we shall reduce blurred noise. In this paper, we introduce the backward solution of nonlinear wave equation for reducing blurred noise and biased expansion of equilibrium contour. We propose, after applying the introduced method, and calculate with discretization method. To analysis the experimental result, we investigate to PSNR and get about 4dB better than current method.

• Journal of radiological science and technology
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• v.45 no.2
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• pp.145-150
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• 2022

The main purpose of this work was to restore the blurry chest CT images by applying a blind deconvolution algorithm. In general, image restoration is the procedure of improving the degraded image to get the true or original image. In this regard, we focused on a blind deblurring approach with chest CT imaging by using digital image processing in MATLAB, which the blind deconvolution technique performed without any whole knowledge or information as to the fundamental point spread function (PSF). For our approach, we acquired 30 chest CT images from the public source and applied three type's PSFs for finding the true image and the original PSF. The observed image might be convolved with an isotropic gaussian PSF or motion blurring PSF and the original image. The PSFs are assumed as a black box, hence restoring the image is called blind deconvolution. For the 30 iteration times, we analyzed diverse sizes of the PSF and tried to approximate the true PSF and the original image. For improving the ringing effect, we employed the weighted function by using the sobel filter. The results was compared with the three criteria including mean squared error (MSE), root mean squared error (RMSE) and peak signal-to-noise ratio (PSNR), which all values of the optimal-sized image outperformed those that the other reconstructed two-sized images. Therefore, we improved the blurring chest CT image by using the blind deconvolutin algorithm for optimal approach.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.1
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• pp.14-22
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• 1980

The Fourier convolution algorithm is used to reconstruct a 34 density function from projection data sets. The convolved data are then back-projected to obtain a density function. There are several choices of the weighting function for the design of the reconstruction(deblurring) filter. Present Paper reviews the published reconstruction liters theoretically and proposes a new reconstructirm filter design method, considering the problems such as the effects of sampling rate, aliasing, and noise. Several previous reconstructirn filters are compared with the proposed filter by computer simulations.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.11a
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• pp.204-205
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• 2019

영상 보안 시스템에 사용되는 일반적인 CCTV 로 획득한 영상에서의 움직이는 피사체의 화질은 좋지 않다. 본 논문에서는 주변광을 정의하고 이를 통해 외부조명 조건하에 획득한 영상의 모션 디블러링을 위한 PSF 패턴을 최적화하여 영상의 화질을 개선하는 방법을 제안한다. 제안하는 알고리즘은 외부조명 동작 패턴에 주변광을 분석한 패턴을 더하여 영상복원을 수행하기 위한 PSF 패턴을 생성한다. 제안한 방법으로 최적화된 PSF 패턴을 사용하여 영상을 복원한 결과 기존에 사용된 방법에 비해 주관적 화질이 향상됨을 확인할 수 있다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2009.01a
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• pp.177-180
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• 2009

볼록거울을 사용하여 CCTV시스템을 만들면 카메라 수를 줄이는 효과가 있다. 이 경우 볼록거울 영상은 휜 영상이므로 평면영상처럼 변환해야 한다. 이 경우에, 중앙에 비추인 영상은 평면 영상으로 변환 후에도 왜곡이 거의 없지만 거울의 테두리 부근에서 얻은 영상을 변환하면 왜곡이 심하게 나타나서 영상 내의 물체를 식별하기가 어려워진다. 렌즈의 초점이 거울의 중심부에 맞춰져 있기 때문에 변에 있는 영상은 픽셀들 사이에 겹침이 일어나기 때문이다. 본 논문에서는 픽셀들 사이의 광학적 겹침을 극복하기 위해 확산 방정식의 후진대입 해를 사용하였다. 결과를 분석하기 위해 PSNR값을 조사하였더니 제안된 방법은 N. Moayeri의 방법보다 4 dB 정도 개선되었다.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.7
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• pp.327-331
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• 2006

We have proposed an image restoration method for a bi-level waveforms whose number of edges is known to us. Based on the information, we parametrize a bi-level waveform using the locations of edges and restore the waveform by estimating the parameter. We estimated the locations by maximizing the correlation coefficients between the hi-level waveform and the measured waveform. In experiments using two dimensional barcode images of the PDF417 specification, the proposed method showed better performance than conventional methods in the sense that the proposed method was able to decode barcode images that were not decoded by the conventional methods.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.53-54
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• 2011

본 논문에서 우리는 동영상에서 인접한 블러되지 않은 참조 프레임을 이용하여 모션 블러를 제거하는 기법을 제안한다. 기존의 디블러링 방법들은 주로 단일 영상을 이용한 방법들로 정확한 커널을 예측하는 것과 원본 영상에 준하는 영상을 복원하는 것에 한계가 존재한다. 하지만 동영상에서 부분적인 프레임에만 블러가 발생한 특수한 경우에는 인접한 위치에 존재하는 블러되지 않은 프레임을 활용하는 것이 가능하다. 제안하는 방법은 블러된 프레임과 인접한 위치에 존재하는 블러되지 않은 프레임 사이에 움직임을 추정하고, 움직임 보상된 영상을 이용하여 커널을 추정한다. 또한 움직임 오차에 따른 잔여 오차 성분에 대해서만 디컨벌루션을 적용하여 물결현상이 억제된 최종적인 결과 영상을 생성한다. 실험 결과는 제안한 방법이 기존의 디블러링 기법에 비해 에지 부분을 잘 복원시키면서 물결현상은 감소된 보다 우수한 디블러링 결과를 가져오는 것을 보여준다.

• Journal of the Chungcheong Mathematical Society
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• v.31 no.1
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• pp.137-149
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• 2018

In this paper, under the assumption of the symmetry point spread function, antireflective boundary conditions(AR-BCs) are considered in connection with the fast truncated Lagrange(FTL) method. The FTL method is proposed as an image restoration method for large-scale ill-conditioned BTTB(block Toeplitz with Toeplitz block) and BTHHTB(block Toeplitz-plus-Hankel matrix with Toeplitz-plus-Hankel blocks) linear systems([13, 17]). The implementation and efficiency of the FTL method in the AR-BCs are further illustrated. Especially, by employing the AR-BCs, both the continuity of the image and the continuity of its normal derivative are preserved at the boundary. A reconstructed image with less artifacts at the boundary is obtained as a result.