• Journal of information and communication convergence engineering
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• 제9권5호
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• pp.591-596
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• 2011

Image denoising is a key issue in all image processing researches. Generally, the quality of an image could be corrupted by a lot of noise due to the undesired conditions of image acquisition phase or during the transmission. Many approaches to image restoration are aimed at removing either Gaussian or impulse noise. Nevertheless, it is possible to find them operating on the same image, which is called mixed noise and it produces a hard damage. In this paper, we proposed noise type classification method and a mixed nonlinear filter for mixed noise suppression. The proposed filtering scheme applies a modified adaptive switching median filter to impulse noise suppression and an efficient nonlinear filer was carried out to remove Gaussian noise. The simulation results based on Matlab show that the proposed method can remove mixed Gaussian and impulse noise efficiently and it can preserve the integrity of edge and keep the detailed information.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권10호
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• pp.611-617
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• 2003

A mechanical or electrical stimulation to the mandibular symphysis during a maximal voluntary clenching of the teeth always produces a jaw jerk followed by a silent period (transient stops) in the masseteric EMG (electromyogram). Generally, a mechanical stimulation is followed by a single silent period, and an electrical stimulation is followed by multiple silent periods. In this paper, we propose a new algorithm for determining the duration of the masseter silent period. The decision approach in essentially based upon a segmentation algorithm consisted of variance filter, median filter and gaussian filter. The new adaptive digital notch filter using R-CLMS(reverse constrained least mean-squared) algorithm is proposed for the elimination of powerline(60Hz) noise. At the same time, we design a real time measurement system for the EMG silent period under Window base.

• 한국정보통신학회논문지
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• 제15권11호
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• pp.2474-2479
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• 2011

사회가 고도의 디지털 정보화 시대로 급속히 발전함에 따라 영상 및 음성 데이터 획득, 전송, 저장을 위한 멀티미디어 통신 서비스가 상용화 되어가고 있다. 그러나 여전히 데이터를 처리하는 과정에서 다양한 잡음에 의해 영상의 열화가 발생하고 있으며 이러한 잡음제거에 관한 연구는 지금까지 계속되고 있다. 따라서 본 논문에서는 임펄스 잡음을 제거하기 위해, 잡음 신호의 판단과 제거 등 두 과정으로 구성된 변형된 적응 스위칭 메디안 필터를 제안하였다. 제안한 알고리즘은 잡음 신호만을 제거하고 비잡음 신호는 그대로 보존하여, 우수한 에지 보존특성 및 잡음제거 능력을 나타내었다. 그리고 개선 효과의 판단 기준으로 PSNR(peak signal to noise ratio)을 사용하였으며, 객관적인 판단을 위해 기존의 방법들과 비교하였다.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권8호
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• pp.360-367
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• 2002

In this paper, genetic algorithm based adaptive image enhancement filtering scheme is proposed and Implemented on FPGA board. Conventional filtering methods require a priori noise information for image enhancement. In general, if a priori information of noise is not available, heuristic intuition or time consuming recursive calculations are required for image enhancement. Contrary to the conventional filtering methods, the proposed filter system can find optimal combination of filters as well as their sequent order and parameter values adaptively to unknown noise types using structured genetic algorithms. The proposed image enhancement filter system is mainly composed of two blocks. The first block consists of genetic algorithm part and fitness evaluation part. And the second block consists of four types of filters. The first block (genetic algorithms and fitness evaluation blocks) is implemented on host computer using C code, and the second block is implemented on re-configurabe FPGA board. For gray scale control, smoothing and deblurring, four types of filters(median filter, histogram equalization filter, local enhancement filter, and 2D FIR filter) are implemented on FPGA. For evaluation, three types of noises are used and experimental results show that the Proposed scheme can generate optimal set of filters adaptively without a pioi noise information.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2004년도 춘계종합학술대회
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• pp.149-153
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• 2004

본 논문은 처리속도와 호환성을 고려하여 DSP프로세서를 이용한 영상의 임펄스 노이즈 제거 필터 설계에 관한 연구이다. 시스템의 하드웨어 구현은 32비트 DSP 독립타겟보드 및 CCD 카메라에서 NTSC 영상의 입력을 획득하는 비전보드로 구성되며 시스템 제어를 위한 호스트 컴퓨터로 구성된다. 디노이징 기법은 적응 미디언 필터를 적용하였다. 실험결과 90%와 PSNR 22㏈정도의 제거 효과가 있다.

• Journal of Astronomy and Space Sciences
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• 제15권1호
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• pp.175-182
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• 1998

SAR 영상은 speckle 잡음의 multiplicative 특성으로 인해 영상 해석에 많은 제약을 받고 있다. Speckle 잡음을 제거하기 위한 방법은 크게 여러 개의 독립 영상을 multi-looks 처리 방법과 디지털 영상 처리 기술을 이용하는 방법으로 speckle 잡음 특성에 따른 비선형필터의 적용이다. 본 연구에서는 국지적 통계 자료를 이용하는 LEE와 Refined LEE 필터 그리고 speckle 자체의 통계 특성을 이용하는 EPOS(Edge Preserving Optimal Speckle)필터를 이용하여 speckle 잡음을 제거하여 SAR 영상의 화질을 개선하고 그 결과를 기존의 mean과 median 필터와 비교하였다.

• ETRI Journal
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• 제37권4호
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• pp.752-765
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• 2015

We propose a novel post-processing algorithm and its very-large-scale integration architecture that simultaneously uses the passive and active stereo vision information to improve the reliability of the three-dimensional disparity in a hybrid stereo vision system. The proposed architecture consists of four steps - left-right consistency checking, semi-2D hole filling, a tiny adaptive variance checking, and a 2D weighted median filter. The experimental results show that the error rate of the proposed algorithm (5.77%) is less than that of a raw disparity (10.12%) for a real-world camera image having a $1,280{\times}720$ resolution and maximum disparity of 256. Moreover, for the famous Middlebury stereo image sets, the proposed algorithm's error rate (8.30%) is also less than that of the raw disparity (13.7%). The proposed architecture is implemented on a single commercial field-programmable gate array using only 13.01% of slice resources, which achieves a rate of 60 fps for $1,280{\times}720$ stereo images with a disparity range of 256.

• 한국통신학회논문지
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• 제18권8호
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• pp.1094-1101
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• 1993

신호를 블러링하여 상관도를 높이고 차이값의 정보량을 줄이는 BDPCM에 의한 영상 압축 가능성을 보인다. 균일한 양자화 간격을 가지고 부호기의 신호 흐름을 분석하여 복호기에서 완전한 신호 복원 능력을 제시한다. 블러링된 신호를 일반적인 DPCM 예측기에 의한 차이값이 일정한 동적 범위에 속한다는 것을 분석한다. 메디안 필터가 임펄스 잡음을 제거할 수 있는 대신에 신호를 철저히 훼손시키는 단점을 개선하기 위해, 차이값에 대해 선택적으로 필터링하는 것을 제안한다. 차이값 분포가 일정하기 때문에 전송중 잡음 특히 임펄스 잡음이 검출되며 필터링에 의해 제거된다. 이로써 저전송률 영상 전송에서 잡음 제거가 가능한 부호기를 제안하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권12호
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• pp.3166-3179
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• 2013

A pre-processing system for adaptive noise removal is proposed based on the principle of identifying and filtering object regions and background regions. Human perception of images depends on bright, well-focused object regions; these regions can be treated with the best filters, while simpler filters can be applied to other regions to reduce overall computational complexity. In the proposed method, bright region segmentation is performed, followed by segmentation of object and background regions. Noise in dark, background, and object regions is then removed by the median, fast bilateral, and bilateral filters, respectively. Simulations show that the proposed algorithm is much faster than and performs nearly as well as the bilateral filter (which is considered a powerful noise removal algorithm); it reduces computation time by 19.4 % while reducing PSNR by only 1.57 % relative to bilateral filtering. Thus, the proposed algorithm remarkably reduces computation while maintaining accuracy.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2007년도 하계종합학술대회 논문집
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• pp.361-362
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• 2007

We propose a contrast-controlled feature detection approach for steel radiograph image. X-ray images are low contrast, dark and high noise image. So, It is not simple to detect defects directly in automated radiography inspection system. Contrast enhancement, histogram equalization and median filter are the most frequently used techniques to enhance the X-ray images. In this paper, the adaptive control method based on contrast limited histogram equalization is compared with several histogram techniques. Through comparative analysis, CLAHE(contrast controlled adaptive histogram equalization) can enhance detection of defects better.