• 한국음향학회:학술대회논문집
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• 한국음향학회 2004년도 춘계학술발표대회 논문집 제23권 1호
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• pp.355-358
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• 2004

최근 웨이블릿 변환을 이용하여 저주파수 부대역 신호를 반복적으로 분해하고 삽입된 워터마크 비트에 따라 특정 부대역 신호에 두개의 다른 반향 중 하나를 삽입하는 반향 삽입 기법을 제안하였다. 이 기법은 오디오 신호의 주파수 특성을 고려했기 때문에 시간 영역에서의 기존의 반향 삽입 기법에 비해 비가청성(inaudibility), 워터마크의 강인성(robustness) 및 용적성(capacity)을 모두 증가시킬 수 있다. 기존의 부대역 신호 기반 반향 삽입 기법이 단일 반향 커널만을 이용하였으나, 본 논문에서는 부대역 신호에 다중 반향 커널을 이용한 반향 삽입 기법을 제안한다. 이 기법은 주관적 왜곡(perceptibility)과 SNR(signal to Noise Ratio)과 같은 객관적인 왜곡 면에서, 원본 오디오 신호의 왜곡을 줄일 수 있다. 실험 결과를 통하여 기존의 방법에 비해 제안된 방법이 SNR과 DR(Detection Rate) 모두 좋은 성능을 보여 제안된 방법의 유효성을 입증하였다.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2007년도 학술대회
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• pp.142-146
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• 2007

Digital Rights Management (DRM) technology has been widely used for protecting the digital contents over the recent years. But the digital contents protected by DRM are vulnerable to various video memory capture programs when DRM packaged contents are decrypted on the consumers' multimedia devices. To make up for this kind of DRM security holes the Forensic Marking (FM) technology is being deployed into the content protection area. Most leading DRM companies as well as big electronics companies like Thomson and Philips already have commercial FM solutions. Forensic Marking technology uses the digital watermarking to insert the user information such as user id, content playing time and etc. into the decrypted and decoded content at the playback time on the consumer devices. When the content containing watermarked user information (Forensic Mark) is illegally captured and distributed over the Internet, the FM detection system takes out the inserted FM from the illegal contents and informs contents service providers of the illegal hacker's information. In this paper the requirements and test conditions are discussed for the commercial Forensic Marking systems.

• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.974-986
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• 2016

Reversible image watermarking, a type of digital data hiding, is capable of recovering the original image and extracting the hidden message with precision. A number of reversible algorithms have been proposed to achieve a high embedding capacity and a low distortion. While numerous algorithms for the achievement of a favorable performance regarding a small embedding capacity exist, the main goal of this paper is the achievement of a more favorable performance regarding a larger embedding capacity and a lower distortion. This paper therefore proposes a reversible data hiding algorithm for which a novel piecewise 2D auto-regression (P2AR) predictor that is based on a rhombus-embedding scheme is used. In addition, a minimum description length (MDL) approach is applied to remove the outlier pixels from a training set so that the effect of a multiple linear regression can be maximized. The experiment results demonstrate that the performance of the proposed method is superior to those of previous methods.

• 한국컴퓨터산업학회논문지
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• 제4권4호
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• pp.647-660
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• 2003

정보가 무형의 재화로 인식되는 상황을 초월해 국방, 치안, 금융, 정치, 교육 등의 광범위한 분야에 위치하고 있는 지식 정보화 시대에서 수많은 정보에 대한 보안의 필요성은 계속해서 증가되고 있는 실정이다. 또한 정보의 바다라고 불리는 인터넷에서의 개인 인증을 위한 아이디(ID)와 패스워드(Password)의 개수 증가에 따른 분실이나 망각, 그리고 도용은 다양한 사회문제를 낳고 있다. 이러한 문제에 대한 대안으로, 생체인식(Biometries)을 비롯한, 서명(Signature), 스마트 카드(Smart Card), 워터마킹(Water-marking)을 통한 여러 인증 시스템들이 개발되고 있다. 따라서 본 논문에서는 이러한 지문의 특성을 이용한 기존 연구결과를 바탕으로 효율성이 좋은 지문 인식 알고리즘 구현을 위한 지문에서의 고유한 특징이 될 수 있는 요소를 추출함을 보여준다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2008년도 추계학술발표대회
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• pp.1500-1503
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• 2008

H.264와 같은 고압축 비디오처리 기법의 등장으로 기존의 MPEG2와 같은 비디오 압축에서 H.264로의 비디오 트랜스코딩이 증가되고 있지만, 고압축 비디오 콘텐츠의 온라인과 오프라인에서 불법배포는 현재 문제가 되고 있다. 본 논문에서는 다이렉트쇼 환경 기반에서 고압축과 저작권 보호를 위한 비디오 트랜스 코딩과 워터마킹을 구현한다. 제안한 방법은 다이렉트쇼의 필터를 이용하여 MPG,WMV를 H.264로 비디오 트랜스코딩을 하고 이와 함께 비디오의 공간영역 특성을 이용하여 저작권 보호를 위한 강인한 워터마킹을 구현한다. 실험 결과 MPG,WMV를 H.264로 트랜스코딩에서 H.264의 QP(Quantization parameter)를 15로 하고 화면간 반복을 10프레임으로 하였을 경우 저작권 보호를 위하여 삽입된 워터마크는 평균 99% 검출됨을 확인하였고, 또한 트랜스코딩중 워터마크삽입에 따른 시간지연은 전체 트랜스코딩시간의 5.7%가 됨을 확인할 수 있었다. 제안한 방법은 저작권 삽입 기능가지는 트랜스코딩 소프트웨어를 필요로 하는 Digital TV방송, IPTV, DVD 사업에 사용 될 수 있을 것이다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 컴퓨터소사이어티 추계학술대회논문집
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• pp.7-10
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• 2003

In this paper, we present a new echo kernel, which is a modification of polar echo kernel. to improve the detection performance and robustness against attacks. Polar echo kernel may take advantage of large detection margin from the polarity of inserted echo signal, but its poor frequency response in low frequency band degrades sound quality. To solve this problem, we applied bipolar echo pulses to the polar echo kernel. Using the proposed echo kernel the distributions of autocepstrum peaks fur data ‘0’ and ‘1’ are located more distant and improvement of detection performance is achieved. It also makes the low frequency band flat so that the timbre difference in the polar echo kernel can be removed to reproduce the imperceptible sound qualify. Informal listening tests as well as robustness test against attacks were performed to evaluate the proposed echo kernel. Experimental results demonstrated the superiority of the proposed echo kernel to both conventional unipolar and polar echo kernels

• Journal of the Optical Society of Korea
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• 제12권3호
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• pp.136-146
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• 2008

We proposed an adaptive steganography of an optical image using bit-planes and multichannel characteristics. The experiment's purpose was to compare the most popular methods used in optical steganography and to examine their advantages and disadvantages. In this paper we describe two digital methods: the first uses less significant bits(LSB) to encode hidden data, and in the other all blocks of $n{\times}n$ pixels are coded by using DCT(Digital Cosine Transformation), and two optical methods: double phase encoding and digital hologram watermarking with double binary phase encoding by using IFTA(Iterative Fourier Transform Algorithm) with phase quantization. Therefore, we investigated the complexity on bit plane and data, similarity insert information into bit planes. As a result, the proposed method increased the insertion capacity and improved the optical image quality as compared to fixing threshold and variable length method.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(3)
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• pp.69-72
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• 2000

In this paper, a novel algorithm for digital watermarking is proposed. We use two pattern keys from BCH (15, 7) code and one randomizing key. In the embedding process, optimal watermark coefficients are determined by statistical analysis of the DCT coefficients from the standpoint of HVS. In the detection, watermark coefficients are restored by correlation matching of the possible pattern keys and minimizing the estimation errors. Attacks tested in the experiments ate image enhancement and image compression (JPEG). Performance is evaluated by BER of the logo images and SNR/PSNR of the restored images. Our method has higher performance against JPEG attacks. Analysis for the performance is included.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 컴퓨터소사이어티 추계학술대회논문집
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• pp.163-166
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• 2003

In conventional patchwork, the difference of the mean values of two groups is compared for watermark detection. We propose two modified patchwork schemes based on order statistics, which achieves significant improvements over conventional patchwork. First, we propose that the mean comparison is replaced by the median comparison, to get PSNR improvement due to informed watermarking. Second, we propose a majority voting scheme of a sequential comparison of pixel pairs in a sorted order, which produces significantly lower BER. The performance improvements are mathematically analyzed and tested. In experimental results, PSNR is about 5㏈～10㏈ higher in the first method and BER is about 1/5～l/2 times lower in the second method than conventional patchwork.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권3호
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• pp.108-111
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• 2002

This paper proposes an new water mark embedding and extraction technique which extends the direct sequence spread spectrum technique. The proposed technique approximates the complexity of image and block in spatial domain using Laplacian filtering and watermark is adaptively embedded in the mid-frequency DCT components. Local parity bits are attached to higher-frequency DCT components and they are used to detect extraction errors and correct those errors. In extraction process the proposed method boosts the higher frequency components of image and extracts the watermark by demodulation and this information is verified and adjusted by parity bits. Experimental results show it is invisible and robust to several external attacks.