• 펄프종이기술
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• 제41권3호
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• pp.35-41
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• 2009

The new way of utilization of Hanji need to develop for adding high value added. An watermarked Hanji was prepared with non-mulberry mixed fibers and the properties were investigated. The mechanical properties of non-mulberry fiber mixed Hanji were very similar to mulberry fiber Hanji. The non-mulberry fiber mixed Hanji was a little brighter than original Hanji. The air permeability and pore size of the hot pepper fiber mixed Hanji were decreased depending on the content of hot pepper fiber. The printing ability of watermarked Hanji made of non-mulberry mixed fibers was higher than that of original paper mulberry Hanji. The preservation properties of non-mulberry fiber mixed watermarked Hanji were almost same as those of the original Hanji.

• 한국콘텐츠학회논문지
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• 제11권1호
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• pp.9-15
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• 2011

제로-워터마킹은 디지털 콘텐츠에 워터마크를 삽입하지 않음으로써 데이터 왜곡과 품질 저하를 피할 수 있는 디지털 워터마킹 기법이다. 이 논문에서는 DCT 영역에서 CRT를 기반으로 한 제로-워터마킹 기법인 DCT0CRT를 제안한다. 무질서한 방식으로 선택된 DCT 블록의 DC 또는 낮은 주파수의 AC 계수들 중에서, 워터마크 정보와 매칭되는 CRT 기반 조건을 만족하는 것을 선택하고, 이러한 선택 정보를 키로 생성함으로써, DCT 영역에서 제로-워터마킹이 가능하도록 지원한다. 이 워터마킹 기법은 이미지에 어떤 변경도 하지 않기 때문에, 이 워터마킹 기법을 적용한 이미지의 품질은 다른 CRT 기반 워커마킹 기법에 비하여 우수하며, 샤프닝, 블러링, JPEG 손실 압축 등을 이용한 공격에도 워터마크가 강인함을 보여준다.

• 융합신호처리학회논문지
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• 제13권4호
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• pp.187-193
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• 2012

An image authentication scheme for gray scale image through embedding a digital watermark by quantization of Integer Wavelet Transform (IWT) coefficients of the image is proposed in this paper. Proposed method is designed to detect modification of an image and to identify tampered location of the image. To embed the watermark mid-frequency band of a second level IWT was used. An approximation of the original image based on LL band was stored in LSB bits of the pixel data as a recovery mark for restoration of the image. Watermarked image has achieved a good PSNR of 40 dB compared to original cover image. Restored image quality was also very good with a PSNR of more than 35 dB compared to unmodified watermarked image even when 25% of the received image is cropped. Thus, the proposed method ensures a proper balance between the fidelity of the watermarked image and the quality of the restored image.

• 한국인터넷방송통신학회논문지
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• 제14권2호
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• pp.17-22
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• 2014

모바일 정지영상 동영상 등의 정보에 디지털 신호를 삽입하여 저작권을 주장하는 방안으로 워터마킹 알고리즘을 들 수 있다. 본 논문에서는 영상의 양자화 계수를 이용한 이산 코사인 변환(DCT)을 기반으로 하는 워터마킹 알고리즘 방법을 제안하였다. 워터마크 삽입 기법은 디지털 원영상의 DCT와 양자화를 통하여 계수들(Quantized Coefficient)를 얻게 되었고, 양자화 계수들은 원하는 위치(Key)에 따라 DCT를 기반으로 한 워터마크(DCT-based watermark)를 삽입하게 되었다. 워터마크가 삽입된 부호화 정보는 역 양자화와 역 DCT를 통하여 워터마크 된 영상을 얻게 된다. 워터마크 추출 기법은 워터마크된 영상과 위치(Key)만을 사용하며, 워터마크 된 영상을 DCT와 양자화를 통하여 원하는 위치(Key)에서 계수를 분리하여 역 DCT하여 원 워터마크를 얻을 수 있었다. 모의실험 결과, 워터마크된 영상과 추출된 워터마크에서 영상의 화질(PSNR)과 워터마크의 정규화 상관도 (NC) 에서 만족할 만한 결과를 확인하였다.

• 방송공학회논문지
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• 제9권1호
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• pp.64-73
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• 2004

본 논문에서는 3차원 메쉬 모델에 적용되는 강인한 워터마킹 알고리듬을 제안한다. 제안하는 알고리듬에서 워터마크는 3차원 모델로부터 추출된 2차원 영상에 삽입된다. 이 2차원 영상의 화소 값은 정해진 기준점들로부터 3차원 모델의 표면까지의 거리이며, 이를 거리 영상이라 한다. 워터마크는 거리 영상에 삽입되며, 워터마크된 거리 영상을 이용하여 3차원 모델의 꼭지점 좌표를 변경하면 워터마크가 삽입된 3차원 모델을 얻는다. 워터마크의 추출은 워터마크가 삽입된 모델로부터 거리영상을 얻고, 이 영상에서 워터마크를 추출한다. 워터마크 추출에는 원본 모델이 필요하며 원본과의 정합이 필요하다. 실험을 통해 제안하는 알고리듬이 회전, 병진, 비례조절, 가우스 잡음, 메쉬 간략화, 꼭지점 양자화에 강인함을 확인하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.466-469
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• 2002

Using intelligent information contained within the speech to identify the specific hidden data in the watermarked multimedia data is considered to be an efficient method to achieve the speech digital watermarking. This paper presents the performance comparison between various types of speech codec in order to determine an appropriate one to be used in digital watermarking applications. In the experiments, the speech signal encoded by four different types of speech codec, namely CELP, GSM, SBC and G.723.1codecs is embedded into a grayscale image, and theirs performance in term of speech recognition are compared. The method for embedding the speech signal into the host data is borrowed from a watermarking method based on the zerotrees of wavelet packet coefficients. To evaluate efficiency of the speech codec used in watermarking applications, the speech signal after being extracted from the attacked watermarked image will be played back to the listeners, and then be justified whether its content is intelligible or not.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.478-481
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• 2002

In this paper, the zerotrees of DWT is proposed to be used in a speech based digital watermarking for digital images. Since in this research work the raw speech and its content are used as a watermark signal, in the watermarking scheme, the PCM coded speech signal is embedded into a sequence of images. The performance of the scheme is evaluated by the PSNR obtained from the watermarked images and the strength of attacks the embedded speech signal can survive. Moreover, since in this research work the contents contained in the speech is used to identify the specific information hidden in the embedded signal. The speech signal after being extracted from the watermarked images is played back to the listeners to determine whether its content is intelligible or not. The experimental results show impressive performance of the scheme implementing our proposed technique, judged by the higher robustness obtained form the embedded signal against various types of attack, including brightness/contrast enhancement, Twirling, highpass filtering and JPEG compression standard.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권10호
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• pp.3591-3606
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• 2014

In this paper, a robust watermarking scheme is proposed that uses the scale-invariant feature transform (SIFT) algorithm in the discrete wavelet transform (DWT) domain. First, the SIFT feature areas are extracted from the original image. Then, one level DWT is applied on the selected SIFT feature areas. The watermark is embedded by modifying the fractional portion of the horizontal or vertical, high-frequency DWT coefficients. In the watermark extracting phase, the embedded watermark can be directly extracted from the watermarked image without requiring the original cover image. The experimental results showed that the proposed scheme obtains the robustness to both signal processing and geometric attacks. Also, the proposed scheme is superior to some previous schemes in terms of watermark robustness and the visual quality of the watermarked image.

• 대한전기학회논문지:시스템및제어부문D
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• 제54권12호
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• pp.716-722
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• 2005

In this paper, we propose the audio watermarking algorithm based on the critical band of HAS(human auditory system) without audibly affecting the quality of the watermarked audio and implement the detecting algorithm on the BSS(broadcast synchronizing system) for testing the proposed algorithm. According to the audio quality test, the SNR(signal to noise ratio) of the watermarked audio objectively is 66dB above. In the robustness test, the proposed algorithm can detect the watermark more than $90\%$ from various compression(MP3, AAC), A/D and D/A conversions, sampling rate conversions and especially asynchronizing attacks. The BSS automatically switches the programs between the key station and the local station in broadcasting system. The result of reliability test of implemented system by using the real broadcasting audio has no false positive error during 30 days. Because of detecting once processing per 0.5 second, we can judge that the false positive error does not occur.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.219-222
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• 2006

In this paper we present a cryptanalysis of the generalized patchwork algorithm under the assumption that the attacker possesses only a single copy of the watermarked audio. In the scheme, watermark is inserted by modifying randomly chosen DCT values in each block of the original audio. Towards the attack we first fit low degree polynomials (which minimize the mean square error) on the data available from each block of the watermarked content. Then we replace the corresponding DCT data of the at-tacked audio by the available data from the polynomials to construct an attacked audio. The technique nullifies the modification achieved during watermark embedding. Experimental results show that recovery of the watermark becomes difficult after the attack.