• Journal of Information Processing Systems
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• 제13권5호
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• pp.1183-1202
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• 2017

Image restoration has been carried out by texture synthesis mostly for large regions and inpainting algorithms for small cracks in images. In this paper, we propose a new approach that allows for the simultaneous fill-in of different structures and textures by processing in a wavelet domain. A combination of structure inpainting and patch-based texture synthesis is carried out, which is known as patch-based inpainting, for filling and updating the target region. The wavelet transform is used for its very good multiresolution capabilities. The proposed algorithm uses the wavelet domain subbands to resolve the structure and texture components in smooth approximation and high frequency structural details. The subbands are processed separately by the prioritized patch-based inpainting with isophote energy driven texture synthesis at the core. The algorithm automatically estimates the wavelet coefficients of the target regions of various subbands using optimized patches from the surrounding DWT coefficients. The suggested performance improvement drastically improves execution speed over the existing algorithm. The proposed patch optimization strategy improves the quality of the fill. The fill-in is done with higher priority to structures and isophotes arriving at target boundaries. The effectiveness of the algorithm is demonstrated with natural and textured images with varying textural complexions.

• 한국정보처리학회논문지
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• 제7권6호
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• pp.1980-1987
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• 2000

In this paper, an efficient watermarking technique in wavelet transform domain is proposed. Watermarking is embedding a digital signal called as 'watermark' into images to claim the ownership. In the proposed method, the image is 1-level wavelet transformed, and then the watermark with a binary stamp is embedded into the baseband. The watermark is embedded by inverting the polarities of he selected coefficient paris. In the inverting process, we can increase image quality by finding means and differences of the selected neighboring coefficient paris, and then adding values, which are inversely proportional to the differences, to th means. The experimental results show that the proposed method has good quality and is robust to various attacks such as the JPEG lossy comparison, noise addition, clipping, blurring, etc.

• Journal of Information Processing Systems
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• 제13권1호
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• pp.68-82
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• 2017

Nowadays, geographic information system (GIS) is developed and implemented in many areas. A huge volume of vector map data has been accessed unlawfully by hackers, pirates, or unauthorized users. For this reason, we need the methods that help to protect GIS data for storage, multimedia applications, and transmission. In our paper, a selective encryption method is presented based on vertex randomization and hybrid transform in the GIS vector map. In the proposed algorithm, polylines and polygons are focused as the targets for encryption. Objects are classified in each layer, and all coordinates of the significant objects are encrypted by the key sets generated by using chaotic map before changing them in DWT, DFT domain. Experimental results verify the high efficiency visualization by low complexity, high security performance by random processes.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2009년도 춘계학술발표대회
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• pp.106-109
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• 2009

Recently, image matching becomes important in Computer Aided Diagnosis (CAD) due to the huge amount of medical images. Specially, texture feature is useful in medical image matching. However, texture features such as co-occurrence matrices can't describe well the spatial distribution of gray levels of the neighborhood pixels. In this paper we propose a frequency domain-based texture feature extractor that describes the local spatial distribution for medical image retrieval. This method is based on 2D Local Discrete Fourier transform of local images. The features are extracted from local Fourier histograms that generated by four Fourier images. Experimental results using 40 classes Brodatz textures and 1 class of Emphysema CT images show that the average accuracy of retrieval is about 93%.

• 한국콘텐츠학회논문지
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• 제11권4호
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• pp.92-100
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• 2011

본 논문에서는 새로운 변환 기법인 셀룰라 오토마타 변환을 이용한 워터마킹 방법과 기존의 DWT를 이용한 방법을 비교한다. 이 두 방법 모두 서로 상반되는 임의의 패턴 정보를 사용하여 워터마크 정보를 영상에 삽입한다. 셀룰라 오토마타 변환은 DWT와 달리 더 많은 정보 즉, 룰 번호, 초기 값, 격자 크기 등 다양한 초기값을 이용하여 기저함수를 생성하여 변환한다. DWT와 셀룰라 오토마타 변환을 이용하여 변환된 영상의 계수를 분석 및 비교한 후 워터마킹 성능을 비교한다. 모의실험에서는 워터마크 정보가 삽입된 영상에 대한 PSNR 및 정규화 상관계수를 이용하여 원영상과의 가시적인 동일성과 다양한 외부 공격에 대한 강인성을 비교한다. 셀룰라 오토마타 변환을 이용한 워터마킹 방법이 DWT를 이용한 방법보다 JPEG 압축, 미디언 필터, 크기 변환, 잘라내기 및 히스토그램 평활화 등 대부분의 공격에 대하여 강인함을 보여준다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2002년도 추계학술대회 및 정기총회
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• pp.427-430
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• 2002

Recently the subject of "wavelet analysis" has be drawn by both mathematical and engineering application fields such as Signal Processing, Compression/Decomposition, Wavelet-Neural Network, Statistics and etc. Even though its similar to Fourier analysis, wavelet is a versatile tool with much mathematical content and great potential for applications. Especially, wavelet transform uses localizable various mother wavelet functions in time-frequency domain. Therefore, wavelet transform has good time-analysis ability for high frequency component, and has good frequency-analysis ability for low frequency component. Using the discriminative ability is more easy method than other conventional techniques. In this paper, Morlet wavelet transform was applied to discriminate the kind of line fault by acquired data from real power transformation network. The experimental result presented that Morlet wavelet transform is easier,and more useful method than the FFT (Fast Fourier Transform).

• 대한전자공학회논문지SP
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• 제42권5호
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• pp.137-144
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• 2005

본 논문에서는 JPEG2000 기반의 영상에서 웨이블릿 영역의 웨이블릿 계수들의 비를 통해 에지 히스토그램을 추출하는 기법을 제시하였다. 기존의 MPEG-7 에지 히스토그램 기술자는 영상의 에지 정보를 공간 영역에서 추출하기 때문에 복호화 과정이 필요하게 되어 많은 연산량이 요구되고 이는 영상 검색 시간을 지연시키는 원인이 된다. 이를 보완하기 위해 JPEG2000 영상의 에지 히스토그램 정보를 공간 영역이 아닌 웨이블릿 영역에서 직접 추출하고자 하였다. 본 논문에서 사용된 웨이블릿 변환은 JPEG2000 표준에서 정한 압축 기법으로 Le Gall 5/3 필터 계수를 사용 하였다. 에지 추출을 위해 웨이블릿 계수들 중에서 2단계 웨이블릿 변환을 통해 얻어진 LH2, HL2 부 밴드의 홀수 번째 계수들의 비와 LHI과 HLI의 계수들을 사용하였다. 실험을 통해 8개의 질의 영상에 대한 NMRR 값을 비교한 결과, 제안 알고리즘에 의한 에지 히스토그램 추출이 기존 에지 히스토그램 기술자와 비교하여 성능이 떨어지지 않았고, 연산량에 있어서도 많은 감소 효과를 얻을 수 있었다.

• 한국정보처리학회논문지
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• 제7권8호
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• pp.2341-2348
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• 2000

현재 동영상 데이터를 이용한 압축영역에서의 특수효과 구현에 많은 관심이 모여지고 있다. 따라서 본 논문에서는 DCT (Discrete Cosine Transform)압축영역에서 다양한 효과를 위해 최소한의 디코더를 개발하였으며, 이를 이용하여 Wipe, Dissolve, Zoom등의 비디오 효과등을 DCT영역에서 제안하였다. 또한 구현한 디코더와 효과들의 확장성과 이식성이 용이하도록 COM기반의 DirectShow 형식으로 각 모듈을 필터화 하였다.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권8호
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• pp.369-374
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• 2006

Due to development of internet network environments and data compression techniques, the size and amount of multimedia data has greatly increased. They are compressed before transmission or storage. Dealing with these compressed data such as video retrieval or indexing requires decompression procedure in most cases. This causes additional computations and increases the processing time. In various applications a histogram is one of the most frequently used tools. Efficiency of extracting such histograms will drop down if decompression is involved. We propose a novel scheme for extracting histograms from images that are transformed into the compressed domain by 8x8 DCT(Discrete Cosine Transform). In this scheme an averaged version of original image is obtained by a simple linear combination of DCT coefficients with the sets of coefficients we designed.

• 한국정보처리학회논문지
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• 제6권10호
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• pp.2716-2721
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• 1999

The problem of determining the conformal maps from the unit disk onto a jordan region has been completed by solving the theodorsen equation that is nonlinear. For the hubners method, which has been well known for the efficient method among the many suggestions for the Theodorsen equation, it has been reproved in our early study that the convergence rate could be remarkably improved by exploring and applying a low-frequency pass filter[1]. However, in the Hubner's method with the low-frequency filter, the discrete numbers and parameters of the low-frequency filter were able to be acquired only by experience. In this paper we show algorithms that determine the discrete numbers and parameters of the low-frequency filter automatically in accordance with the given region. This results from analyzing the function, which decides the shape of the given domain under the assumption that the degree of the problem depends of the transformation of a given domain, as seen in the Fourier Transform.