• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.260-263
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• 2003

The pseudocolor mage enhancement of gray image using wavelet filter coefficients is presented. The psuedocolor enhancement is that the decomposition enhancement is realized by wavelet transform and RGB image is extracted by wavelet filter coefficients with norma waveletl. The result of experiment an increases enhanced gray image as 30dB compared the processing of wavelet filter coefficients.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.305-307
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• 2009

본 논문에서는 기존의 퍼지 논리를 이용한 필터링 알고리즘의 문제점을 개선하는 동시에 컬러 영상에 적용할 수 있는 퍼지 필터 알고리즘을 제안한다. 제시된 퍼지 필터 알고리즘은 영상의 RGB 컬러 정보를 각각의 R, G, B 채널 영상으로 분리하고, 각 채널 영상에서 마스크가 위치한 기준 픽셀의 잡음 가능성 정도를 퍼지 논리에 적용하여 판단한다. 잡음 정도에 따라서 출력 영상의 화소값을 평균값 또는 중간값으로 결정한다. 제안된 방법을 잡음이 존재하는 칼라 영상에 적용한 결과, 단색 정보를 기준으로 처리하는 기존의 퍼지 필터 방법에 비해서 효과적인 것을 확인하였다.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.12
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• pp.105-110
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• 2016

To reduce the cost and volume of a digital camera, a subsampled color filter array(CFA) image is used and demosaicking is applied to estimate the missing color values. However, aliasing, the overlaps of signals in the frequency domain, occurs when signals are subsampled. This causes aliasing artifacts such as false colors and zipper effects in demosaicking processes. In this paper, the algorithm estimating high-quality color images by removing aliasing artifacts in them is proposed. The aliasing region map is estimated using the sub-sampled signals of the CFA image. By using the aliasing region map and the estimated luminance image, the least squares problem of the observation models is designed and aliasing artifacts are eliminated. The experiments demonstrate that the proposed algorithm restores color images without aliasing artifacts.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.4
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• pp.68-74
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• 2017

This paper presents a joint demosaicking and arbitrary-ratio down sampling algorithm for color filter array (CFA) images. Color demosaiking is a necessary part of image signal processing pipeline for many types of digital image recording system using single sensor. Also, such as smart phone, obtained high resolution image from image sensor has to be down-sampled to be displayed on the screen. The conventional solution is "Demosaicking first and down sampling later". However, this scheme requires a significant amount of memory and computational cost. Also, artifacts can be introduced or details get damaged during demosaicking and down sampling process. In this paper, we propose a method in which demosaicking and down sampling are working simultaneously. We use inverse mapping of Bayer CFA and then joint demosaicking and down sampling with arbitrary-ratio scheme based on signal decomposition of high and low frequency component in input data. Experimental results show that our proposed algorithm has better image quality performance and much less computational cost than those of conventional solution.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.216-218
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• 2010

본 논문에서는 기존의 퍼지 필터링 알고리즘의 문제점을 개선한 퍼지 필터링 기법을 제안한다. 제안된 퍼지 필터링 알고리즘은 컬러 영상에서 R, G, B 채널을 각각 분리한다. 분리된 각 채널에서 마스크 정보를 추출하여 채널에 대한 평균값과 중간값의 명암도를 제안된 퍼지 기법의 소속 함수에 적용하여 소속도를 구한 뒤, 추론 규칙에 적용한다. 그리고 R, G, B 각각의 소속도 값을 이용하여 잡음 가능성 여부를 판별한다. 제안된 퍼지 기법에서 소속 함수 구간은 세 개 구간으로 설정하였다. 잡음이라고 판단되는 경우에는 그 잡음 정도에 따라 중간값이나 평균값을 해당 픽셀 값으로 설정하여 잡음을 제거한다. 제안된 기법을 컬러 영상에 적용한 결과, 제안된 기법이 기존의 퍼지 필터링 기법보다 잡음 제거에 있어서 효과적인 것을 확인할 수 있었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.522-527
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• 2000

본 논문은 그레이이미지를 컬러이미지로 변환하는 의사칼라이미지 향상에 관한 연구이다. 적용기법은 그레이이미지의 시간영역신호를 주파수영역으로 변환하고 LPF, BPF, HPF 2차원필터를 통과시켜 시간영역으로 역 변환한 후 각각에 대해 히스토그램 평활화하여 RGB 신호를 구하는 과정에서 의사 칼라를 얻는다. 실험 결과 필터주파수가 증가함에 따라 PSNR도 증가하고 낮게 설정하면 경계부분의 화질이 좋아진다. 2차원 주파수필터의 사용은 칼라 변환 시 강조하고자 하는 부분을 보다 자유롭게 변환할 수 있고 다양한 컬러 이미지로 향상되어 영상분석에 효과가 있다. 의사칼라의 변환에 의한 식별 인식능력은 9dB 정도 향상된다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.72-80
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• 2009

Look-up table based inverse halftoning from the digital color halftone image is proposed in this paper, which uses vector adaptive filter for the nonexisting patterns in the table. Halftone image is obtained from a continuous -tone image, which can be restored into continuous one from the digital binary image by way of inverse halftoning method. Look-up table based method usually processes fast and has even performances over the various halftoning. The numbers of pixels in the pattern of table and the method how to define the table elements for each R, G, B channels can effect largely for its performance. The proposed method uses 16 pixels in the table considering the diversity of the expressions from their patterns and with memory size as well. This also proposed how to combine R, G, B channels into one. Experimental results showed the better performance in the expression of colors, better color restoration and the short processing time compared with the conventional ones.

• Journal of Korean Electronics
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• v.24 no.9
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• pp.24-25
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• 2004

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12C
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• pp.1138-1146
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• 2009

Digital cameras adopting a single CCD detector collect image color by subsampling in three color planes and successively interpolating the information to reconstruct full-resolution color images. Therefore, to recovery of a full-resolution color image from a color filter array (CFA) like the Bayer pattern is generally considered as an interpolation issue for the unknown color components. In this paper, we first calculate luminance component value by combining R, G, B channel component information which is quite different from the conventional demosaicing algorithm. Because conventional system calculates G channel component followed by computing R and B channel components. Integrating the obtained gradient edge information and the improved weighting function in luminance component, a new edge sensitive demosaicing technique is presented. Based on 24 well known testing images, simulation results proved that our presented high-quality demosaicing technique shows the best image quality performance when compared with several recently presented techniques.

• Journal of Broadcast Engineering
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• v.16 no.3
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• pp.561-565
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• 2011

This paper presents an imaging system for reconstruction of enhanced color images using the conventional Bayer CFA. By extracting various colors such as RGBCY from two sequential images which consist of a image by broadband G channel lens filter and the other image captured without one, the proposed color image reconstruction system can reduce the computational complexity for demosaicking and make high resolution color information without aliasing artifacts. Because the proposed system uses the common Bayer CFA image sensor, fabricating a new type of CFA is not necessary for obtaining a multi-spectral image, which can be easily extensible for applications of multi-spectral imaging. Finally, in order to verify the performance of the proposed system, experimental results are performed. By comparing with the existing demosaicking methods, the proposed camera system showed the significant improvements in the sense of color resolution.