• 한국통신학회논문지
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• 제28권11C호
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• pp.1118-1122
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• 2003

본 논문에서는 특이치 분해를 이용한 워터마크 기법을 제안하였다. 워터마킹의 단계는 먼저 웨이블릿 변환에 의한 저해상도 LL대역의 영상을 3${\times}$3 블록단위로 나누고, 엔트로피와 조건수를 기준으로 선택한 블록을 특이치 분해하여 워터마크를 삽입하는 것이다. 이는 워터마크 추출을 안정적으로 수행할 수 있는 저 대역 워터마크 삽입기법을 제공한다. 본 논문에서 워터마크를 효율적으로 추출하기 위해 영상에 가해진 공격을 국소적으로 모델링하여 공격연산자를 근사적으로 구하고, 워터마크 삽입 시 수행된 특이치 분해와 추정된 공격연산자를 적용하여 삽입위치에 따라 워터마크 집단을 결정한다. 각 워터마크 집단 내에서 최적의 워터마크를 구하고 T검정을 이용하여 워터마크의 유무를 검정한다. 제안된 워터마크 기법이 여러 단계 JEPG 공격에 견고하다는 것을 수치실험에서 확인하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(4)
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• pp.85-88
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• 2002

In this paper, the proposed watermark algorithm is based on energy distribution of the subband coefficients in the frequency domain and edge of the original image in the spacial domain. Out of these information, the KeyMap which decides the embedded position of watermark is produced. And then the binary watermark is embedded into the wavelet coefficient of LL3 subband using KeyMap and LFSR(Linear Feedback Shift Register).

• 한국통신학회논문지
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• 제31권4C호
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• pp.458-471
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• 2006

Digital watermarking of multimedia data is a very active research area that has enjoyed a considerable amount of attention in recent years. In this paper, we propose an algorithm for embedding/detecting a fragile watermark in MPEG-4 compressed video domain (Simple and Advance Simple Profiles). The watermark bits are put directly into Huffman VLC-codespace of quantized DCT domain. The advantage of watermark embedding into the compressed domain is the significant savings for a real-time implementation as it does not require a full decoding operation. The watermark embedding does not change the video file size. The algorithm demonstrates high watermarking capacity, thereby providing reliable foolproof authentication. The results of experimental testing demonstrate that watermark embedding preserves the video quality. Watermark detection is performed without using the original video.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.407-410
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• 2003

We propose a new logo watermark scheme for digital images which embed a watermark by modifying middle-frequency sub-bands of wavelet transform. Independent component analysis (ICA) is introduced to authenticate and copyright protect multimedia products by extracting the watermark. To exploit the Human visual system (HVS) and the robustness, a perceptual model is applied with a stochastic approach based on noise visibility function (NVF) for adaptive watermarking algorithm. Experimental results demonstrated that the watermark is perfectly extracted by ICA technique with excellent invisibility, robust against various image and digital processing operators, and almost all compression algorithms such as Jpeg, jpeg 2000, SPIHT, EZW, and principal components analysis (PCA) based compression.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.225-228
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• 2005

According to a popularization of the Internet and digital lifestyle, digital watermarks have been proposed for protection of copyrighted multimedia content. In blind watermark detection, which an original image is not provided, robustness against geometric distortion and compression remains challenging. In this paper, we propose a new perceptual blind discrete wavelet transform - discrete Fourier transform (DWT-DFT) composite watermarking scheme that is robust against both general linear transform and JPEG compression. This algorithm constructs an image-dependent watermark in the most significant DWT coefficients, which is determined by using a hierarchical tree structure. Strength of watermark is determined from a just-noticeable difference (JND) profile of a perceptual model. Furthermore, a desired template is inserted into DFT domain of the watermarked image. In new manner, a cross-ratio of four collinear points is used for detecting the template. Experimental results have showed that the proposed scheme is robust against general linear distortion, JPEG compression and various general kinds of attacks in the Stirmark 3.1 watermark evaluation tool.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.868-871
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• 2002

Nowadays, zerotrees based digital watermarking techniques are considered to be an efficient watermarking technique used for multimedia data in a compressed form. This paper presents a technique for watermarking an image, by employing zerotrees derived from the wavelet packet coefficients of the transformed image to carry the watermark signal. By setting a proper threshold in zerotrees determining process, the watermark signal can be recovered without the need of original image. With our proposed technique, more amount of watermark signal can be embedded within the image, compared to ordinary wavelet transform based techniques. The experimental results show the improved performance in both qualities of the resultant watermarked image and robustness of the embedded watermark signal against common signal processing such as brightness/contrast enhancement, high-pass filtering, Gaussian noise adding and JPEG compression scheme

• 전기학회논문지
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• 제56권11호
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• pp.2027-2032
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• 2007

In this paper, digital watermarking method using quad-tree algorithm and the lowest frequency band is proposed. The proposed algorithm searches the coefficient of the watermark by using quad-tree algorithm and inserts the watermark by the Cox's algorithm. The simulation of the proposed algorithm is implemented about the effect of various weight factors in Cox's algorithm, that of embedding watermark in each subband coefficient (HH, LH, HL), and that of embedding in the lowest frequency band (LL). As a simulation result, the bigger weight factors in Cox's algorithm show strong to noise. The watermarking performance of simultaneously embedding in HH, LH, and HL band is better than that of different cases. In addition, insertion the watermark to the LL band about $30{\sim}60%$ of all watermarks improves the watermarking performance in comparison with the case of not using the LL band.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 G
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• pp.2427-2429
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• 1998

Digital watermarking is the techinque which embeds the invisible signal into multimedia data such as audio, video, images, for copyright protection, including owner identification and copy control information. This paper proposes a new watermark embedding and extraction technique by extending the direct sequence spread spectrum technique. The proposed technique approximates the frequency component of pixels in spatial domain by using Laplacian mask and adaptively embeds the watermark considering the HVS to reduce the degradation of Image. In watermark extraction process, the proposed technique strengthens the high frequency components of image and extracts the watermark by demodulation. All this processes are performed in spatial domain to reduce the processing time.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(3)
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• pp.125-128
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• 2000

In this paper, we proposed the high quality digital audio watermarking algorithm in the frequency domain. The spread spectrum technique is used to encrypted a stream of information by spreading the data as much of the frequency spectrum as possible. It's technique adapt well to data hiding in audio signal. We have used the perceptual model and MDCT/IMDCT for the high qualify digital audio watermarking. The proposed watermark algorithm preserved high quality audio data from watermark signal.

• 한국소프트웨어감정평가학회 논문지
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• 제16권2호
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• pp.143-151
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• 2020

인터넷을 기반으로 하는 디지털 컨텐츠 응용 분야에서 디지털 콘텐츠의 보안 및 인증은 매우 중요하다. 특히, 콘텐츠의 인증을 수행하는 방법에는 여러 가지가 있다. 디지털 워터 마킹은 이와같은 방법 중 하나이다. 특히, 논문은 디지털 이미지의 응용에서 동작하는 디지털 워터마크 기반 인증 방법을 제시한다. 제안 된 워터마크는 3 상태 정보를 가지고 있으며 참조 콘텐츠 없이 임베딩 및 검출을 수행하는 블라인드 워터마킹 방법이다. 디지털 콘텐츠의 소유자 정보를 인증 할 때 자기 상관 함수를 사용한다. 또한, 주파수 영역(DWT Domain)에서 원본 콘텐츠의 신호에 적응적이도록 대역 확산(Spread Spectrum) 방식을 사용한다. 따라서 은닉정보의 검출에서 일어나는 오류의 가능성을 줄였다. DWT에서의 워터마킹은 다른 변환 방법 (DFT, DCT 등)보다 빠른 은닉/검출의 장점을 가진다. 크기가 N=m X m인 이미지를 사용할 때의 계산량은 2상태 워터마크는 O (N·logN)인 반면 O (N)으로 줄어들 수 있다. 가장 우수한 장점은 비트 당 더 많은 정보를 숨길 수 있다는 것이다.