• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.11
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• pp.2717-2723
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• 2015

Recently, digital image processing is being applied in various areas of broadcasting, communication, computer graphic and medical science. But, degradation of images occurs in the process of digital image acquisition, processing and transmission. Therefore, in order to remove the mixed noise, this paper suggested the image restoration algorithm to process salt and pepper noise with weighted filters according to 4 direction pixel changes after judging the noise and to process AWGN with weighted filters which have individually different characteristics. Regarding the processed results by applying Boat images which were corrupted by salt and pepper noise(P=40%), suggested algorithm showed the improvement by 1.33[dB], 1.41[dB], 0.51[dB] respectively compared with the existing CWMF, AWMF, MMF.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.11a
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• pp.127-130
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• 2008

본 논문에서는 아날로그 TV에서 사용되는 인터레이스 영상을 디지털 디바이스에서 보다 우수하게 출력하기 위해 새로운 디인터레이싱 알고리듬을 제안 한다. 기존의 에지 기반의 라인 평균 방법의 경우 제한된 방향의 화소단위 상관도를 이용하기 때문에 잡음과 계조도 변화에 취약하였다. 또한 공간적 방향 벡터를 사용한 DOI방법은 영상 내 수평 에지가 강한 영역을 보간하는데 우수하지만 좌우 넓은 검색 영역으로 인한 잡음에 취약한 단점이 있었다. ED4D는 에지기반 라인 평균 방법과 공간적 방향 벡터를 적절히 사용하여 규칙적 에지 특성을 갖는 영역에 대한 에지 방향의 정확도를 높였다. 하지만, 참조 방향 및 화소 보간의 판별 기준이 $3{\times}2$ 윈도우로 고정되어 있기 때문에 초기 방향성 판단 기준과 수평 방향 에지 검출에 있어 정밀도가 떨어지는 문제점을 안고 있다. 제안하는 방법은 기존에 사용하던 $3{\times}2$ 윈도우에 $5{\times}2$ 윈도우를 추가적으로 적용하여 초기 방향성 판단 기준을 더 섬세하게 하였으며, 변형된 공간적 방향 벡터를 사용하여 넓은 검색영역으로 인한 잡음의 간섭을 줄였다. 실험결과를 통하여 제안한 방법이 기존의 방법에 비해 주관적 화질뿐만 아니라 객관적인 성능도 우수함을 알 수 있다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.3
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• pp.598-604
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• 2012

Image signal is corrupted by various noises in image processing, many studies are being accomplished to restore those images. In this paper, we proposed a cascade filter algorithm for removing random valued impulse noise. The algorithm consists two steps that noise detection and noise elimination. Variance of filtering mask and center pixel variance are calculated for noise detection, and the noise pixel is replaced by estimated value which first apply switching self adaptive weighted median filter and finally processed by modified weight filter. Considering the proposed algorithm only remove noise and preserve the uncorrupted information that the algorithm can not only remove noise well but also preserve edge.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.394-400
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• 2016

Currently, with the rapid development of the digital age, multimedia-related image devices become popular. However image deterioration is generated by multiple causes during the transmission process, with typical example of salt and pepper noise. When the noise of high density is added, existing methods are deteriorated in the characteristics of removal noise. After judging the noise condition to remove the salt and pepper noise, if the center pixel is the non-noise pixel, it is replaced with the original pixel. On the other hand, if it is the noise pixel, algorithm is suggested by the study, where the histogram of the corrupted image and the median filters are used. And for objective judgment, the proposed algorithm was compared with existing methods and PSNR(peak signal to noise ratio) was used as judgment standard. As the result of the simulation, The proposed algorithm shows a high PSNR of 32.57[dB] for Lena images that had been damaged of a high density salt and pepper noise(P=60%), Compared to the existing CWMF, A-TMF and AWMF there were improvements by 21.67[dB], 18.07[dB], and 20.13[dB], respectively.

• Journal of Broadcast Engineering
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• v.20 no.4
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• pp.521-532
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• 2015

This paper presents a piecewise image denoising with multi-scale block region detector based on quadtree structure for effective image restoration. Proposed piecewise image denoising method suggests multi-scale block region detector (MBRD) by dividing whole pixels of a noisy image into three parts, with regional characteristics: strong variation region, weak variation region, and flat region. These regions are classified according to total pixels variation between multi-scale blocks and are applied principal component analysis with local pixel grouping, bilateral filtering, and structure-preserving image decomposition operator called relative total variation. The performance of proposed method is evaluated by Experimental results. we can observe that region detection results generated by the detector seems to be well classified along the characteristics of regions. In addition, the piecewise image denoising provides the positive gain with regard to PSNR performance. In the visual evaluation, details and edges are preserved efficiently over the each region; therefore, the proposed method effectively reduces the noise and it proves that it improves the performance of denoising by the restoration process according to the region characteristics.

• Korean Journal of Remote Sensing
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• v.33 no.2
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• pp.159-169
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• 2017

The Satellite Electro-Optic Payload System needsspecial requirements with the conditions of limited power consumption and the space environment of solar radiation. The acquired image quality should be mainly depend on the GSD (Ground Sampled Distance), SNR (Signal to Noise Ratio), and MTF (Modulation Transfer Function). On the well-manufactured sensor level, the thermal noise is removed on ASP (Analog Signal Processing) using the CDS (Corrective Double Sampling); the noise signal from the image sensor can be reduced from the offset signals based on the pre-pixels and the dark-pixels. The non-uniformity shall be corrected with gain, offset, and correction parameter of the image sensor pixel characteristic on the sensor control system. This paper describes the SNR enhancement method of the satellite EOS payload using the mentioned noise remove processes on the system design and operation, which is verified by tests and simulations.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.3
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• pp.629-635
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• 2017

In this paper, we proposed a nonlinear synthesis filter for noise reduction to reduce the effects of Gaussian noise and impulse noise. When the centralization of the local mask is judged to be Gaussian noise by the noise judgment, the weight value of the weight filter are applied differently according to the spatial weight filter and the pixel change by using the sample variance in the local mask. And if it is determined as the impulse noise, we proposed an algorithm that applies different weights of local histogram weight filter and standard median filter according to noise density of mask. In order to evaluate the performance of the proposed filter algorithm, we used PSNR(peak signal to noise ratio) and compared existing methods and proposed filter algorithm in the mixed noise environment with Gaussian noise, impulsive noise, and two noises mixed.

• Journal of Broadcast Engineering
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• v.6 no.2
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• pp.139-147
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• 2001

Since various noises degrade not only image quality but also compression efficiency in MPEG and H.263, pre-processing is necessary to reduce spatial and temporal noise and to increase ceding efficiency as well. In this paper, we propose a simplified method for noise detection, spatial and temporal noise reduction. Noise detection is based on correlation of the current pixel with its neighboring 4 pixels. Spatial noose reduction utilizes a non-rectangular median filter that is less complex than the conventional rectangular median filter. The proposed temporal filter is an IIR average filter using LUT(Look-up Table) to enhance subjective video quality. The proposed pre-processing method is very simple and efficient.

• Journal of Korea Multimedia Society
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• v.13 no.9
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• pp.1329-1336
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• 2010

Cellular Automata is a discrete dynamical system which natural phenomena may be specified completely in terms of local relation, can increase and decrease the difference of luminance locally according to transition rule by keeping the characteristic of target image. In this paper, we propose a noise reduction method by keeping the characteristic using transition rule of Cellular Automata, also we propose methods of effective transition rule, the selection of parameters, the selection of number of neighborhood pixels. For uniform distribution noise, Gaussian noise, impulse noise, we do an experiment on adaptive state using different mathematical operations and compare its results. It was confirmed that the proposed transition rule is based on fast convergence speed and has stabile results.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.153-156
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• 2006

본 논문에서는 H.264 표준화 기구인 Joint Video Team(JVT) 권고안의 정수 단위 화소 움직임 예측을 위한 Unsymmetrical-cross Multi-Hexagon-grid Search(UMHexagonS) 알고리즘에서 Uneven Multi-Hexagon-grid Search(UMHGS) 부분을 개선한 알고리즘을 제안한다. 제안하는 알고리즘은 이전 프레임의 동일위치 또는 상위 모드에서 이미 선택된 움직임 벡터(MV: Motion Vector)를 이용하여 신호 대 잡음 비(PSNR: Peak Signal to Noise Ratio) 및 평균 비트 율(Average Bitrates)을 유지하면서, 현재 매크로블록의 검색영역을 줄이는 것이 가능하다. 제안하는 알고리즘의 성능은 Full Search Block Matching Algorithm(FSBMA) 및 UMHexagonS 알고리즘의 integer pel 에 대한 SAD(Sum of Absolute Difference) 연산횟수로 비교평가 하였다. 그 결과, FSBMA 에 비하여 평균 97.64%, UMHexagonS 에 비하여는 평균 17.48%의 연산횟수를 감소시키는 우수함을 보였다.