• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.359-363
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• 2009

가역 정보 은닉이 되기 위해서는, 비밀 정보가 삽입된 컨텐츠에서, 삽입된 비밀 정보 뿐만아니라, 원본 컨텐츠를 완벽하게 복구시킬 수 있어야 한다. 이미지 상에서 가역 정보 은닉을 할 때, 데이터의 삽입 용량이 크고, 왜곡이 작도록 설계해야 한다. 본 논문은 삽입 용량을 증가시키기 위해 데이터를 삽입시키는 차분값으로서 예측 오류 값을 이용하였고, 왜곡을 감소시키기 위해서 차분값을 정렬하고, 데이터 삽입 시에 최적화된 히스토그램 이동을 이용하였다. 본 논문에서는 이 세 가지 기술을 조합하여 가역 정보 은닉을 하는데 성공하였고, 최적화된 히스토그램 경계값을 구해내는 알고리즘이 제시되었다.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.2
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• pp.268-274
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• 2010

A steganographic method using three directional data embedding for gray images is presented in this paper. Cover image is divided into non-overlapping $2\times2$ sub-blocks and the basis pixel is selected to calculate the three different values of each sub-block. Difference values are replaced by embedding the number of secret bits that is referenced by the range table. For the three pixel pairs in the sub-block, the optimal pixel adjustment is preceded to reduce the distortion of visual quality. The experimental results show that the proposed method achieves a good visual quality and high capacity.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1811-1814
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• 2003

In this paper, a novel watermarking technique is proposed to authenticate the owner-ship of copyright for the digital contents. Using the 2-level DWT(Discrete Wavelet Transform) we divide a specific frequency band into detailed blocks and apply PIM(picture information measure). After the complexity is calculated, the watermark is embedded in only on high complexity areas. Conventional watermarking technique damages to the original image, because it does not consider the feature of the whole area or a specific frequency band. Easily affected by noise and compression, it is difficult to extract the watermark. However, the proposed watermarking technique, considering the complexity of input image, does not damage to the original image Simulation result show that the proposed technique has the robustness of JPEG compression, noise and filtering such as a general signal processing

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.84-86
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• 2006

An informed watermarking algorithm is proposed in this work that aids in concealing packet loss errors in video communications. This watermark-based error concealment(WEC) method embeds a low resolution version of the video frame inside itself as watermark data. At the receiver, the extracted watermark is used as a reference for error concealment. The proposed DCT-based algorithm has features of informed watermarking in order to minimize the distortion of the host frame. At the encoder, a predictive feedback loop Is employed which helps to adjusts the strength of the scale factor Furthermore, some of the modified coefficients of the DCT signal are virtually free from distortion by employing bit- sign adaptivity. The performance of the detector is Qualitatively analyzed for error concealment applications where full-frame DCT embedding proved to be more advantageous.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.4
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• pp.161-168
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• 2009

There are many research for efficient, robust and invisible watermarking system that protects the digital contents like a image and animation according to growth of IT industry. First of all, frequency domain watermarking system like DWT(Descrete Wavelet Transform) is excellent because of minimum loss of original image and robustness of external attack. But, if we raise the insertion strength of watermark, then blazing of image occurs on existing DWT watermarking system and we should have a regular square image. In this study, we research the overflow check for preventing image from blazing and a robust and invisible watermarking algorithm. And we research a free-size DWT watermarking system using padding bytes, without a dependency of size.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.101-104
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• 2002

This paper proposes a unique data embedding algorithm for the video sequence. It describes two processings: shot boundary detection and robust data embedding. First, for the shot boundary detection, instead of using absolute frame differences, block by block based relative frame differences are employed. Frame adaptive thresholding values are also employed for the better detection. Second, for the robust data embedding, we generate message template and then convolve and correlate it with carrier signal. And then we embed data on the time domain video sequence. By using these two methods, watermarks into randomly selected frames of shots. Watermarks are detected well even if several certain shots are damaged because we embed watermark into each shot equally.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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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.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.9
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• pp.423-428
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• 2006

In this paper we propose a new watermarking scheme using a data matrix and a cryptograph key. The data matrix of two-dimensional bar codes is a new technology capable of holding relatively large amounts of data compared to the conventional one-dimensional bar code. And a cryptograph key is used to prevent a watermark from malicious attacks. We encoded the copyright information into a data matrix bar code, and it was spread as a pseudo random pattern using the owner key. The experimental results show that the proposed scheme has good quality and is robust to various attacks, such as JPEG compression, filtering and resizing. Also the performance of the proposed scheme is verified by comparing the copyright information with the information which is extracted from the watermark.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.5
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• pp.1041-1046
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• 2009

In this paper, we proposed a robust watermark scheme for image based on SVD(Singular Value Transform) and Triplet. First, the original image is decomposed by using 3-level DWT, and then used the singular values changed for embedding and extracting of the watermark sequence in LL3 band. Since the matrix of singular values is not easily altered with various signal processing noises, the embedded watermark sequence has the ability to withstand various signal processing noise attacks. Nevertheless, this method does not guarantee geometric transformation(such as rotation, cropping, etc.) because the geometric transformation changes the matrix size. In this case, the watermark sequence cannot be extracted. To compensate for the above weaknesses, a method which uses the triplet for embedding a barcode image watermark in the middle of frequency band is proposed. In order to generate the barcode image watermark, the pattern of the watermark sequence embedded in a LL3 band is used. According to this method, the watermark information can be extracted from attacked images.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.355-356
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• 2009

점자 체계와 CMYK 모델을 이용하여 시각 장애인과 일반인이 읽을 수 있는 책을 만들기 위한 방법론을 제시한다. CMYK의 K를 이용해 8개의 점으로 구성된 셀 문자를 텍스트에 삽입하여, 텍스트 스캔 시 빠르고 정확한 문자 인식이 가능하게 한다.