• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.11
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• pp.2893-2912
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• 2013

The design of geometrically invariant watermarking is one of the most challenging work in digital image watermarking research area. To achieve the robustness to geometrical attacks, the inherent characteristic of an image is usually used. In this paper, a geometrically invariant image watermarking scheme using connected objects and gravity center is proposed. First, the gray-scale image is converted into the binary one, and the connected objects according to the connectedness of binary image are obtained, then the coordinates of these connected objects are mapped to the gray-scale image, and the gravity centers of those bigger objects are chosen as the feature points for watermark embedding. After that, the line between each gravity center and the center of the whole image is rotated an angle to form a sector, and finally the same version of watermark is embedded into these sectors. Because the image connectedness is topologically invariant to geometrical attacks such as scaling and rotation, and the gravity center of the connected object as feature points is very stable, the watermark synchronization is realized successfully under the geometrical distortion. The proposed scheme can extract the watermark information without using the original image or template. The simulation results show the proposed scheme has a good invisibility for watermarking application, and stronger robustness than previous feature-based watermarking schemes against geometrical attacks such as rotation, scaling and cropping, and can also resist common image processing operations including JPEG compression, adding noise, median filtering, and histogram equalization, etc.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.689-692
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• 2000

본 논문에서는 이동 통신에서 사용될 저 복잡도를 갖는 이진 영상 압축 알고리즘을 제안한다. 기존의 이진영상의 부호화에 사용되는 알고리즘에는 JBIG, G.4등과 같은 방식이 있으나, JBIG의 경우 산술 부호화로 인한 높은 복잡도를 필요로 하고, G.4의 경우 일반 A4 문서를 대상으로 하고 있어 이러한 알고리즘을 이동 통신에서 사용하기에는 부적합하다. 따라서 본 논문에서는 단순한 이진 영상에 대해서 낮은 복잡도를 가지며 기존의 부호화 방식들 보다 좋은 성능을 얻을 수 있는 효과적인 압축 방법을 제시한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.2
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• pp.1-8
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• 2008

The object of watermarking is to prevent from copying and distributing without the copyright or right of ownership. In case of using watermark as an image data we can detect watermark whether an original image exists or not. In this paper, we proposed that an image data is used for watermark and the watermark is detected without an original image. After the original image is transformed with DWT and the watermark is transformed with DCT, they are transformed with binary number. We calculate an optimal bit position for concealing watermark of an original binary image and insert the watermark and determine the best position for robustness against JPEG compression, filtering, and resampling attacks within inserted watermark image. In this paper, we are able to confirm the right of copyright and ownership easily while using invisible watermark and also we can detect a watermark without an original image.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.6
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• pp.33-43
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• 2003

In this paper, we proposed a real-time watermarking algorithm to be combined and to work with a DWT(Discrete Wavelet Transform)-based image compressor. To reduce the amount of computation in selecting the watermarking positions, the proposed algorithm uses a pre-established look-up table for critical values, which was established statistically by computing the correlation according to the energy values of the corresponding wavelet coefficients. That is, watermark is embedded into the coefficients whose values are greater than the critical value in the look-up table which is searched on the basis of the energy values of the corresponding level-1 subband coefficients. Therefore, the proposed algorithm can operate in a real-time because the watermarking process operates in parallel with the compression procession without affecting the operation of the image compression. Also it improved the property of losing the watermark and the efficiency of image compression by watermark inserting, which results from the quantization and Huffman-Coding during the image compression. Visual recognizable patterns such as binary image were used as a watermark The experimental results showed that the proposed algorithm satisfied the properties of robustness and imperceptibility that are the major conditions of watermarking.

• Journal of Korea Multimedia Society
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• v.6 no.5
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• pp.861-869
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• 2003

The rapid growth of multimedia network systems has caused overflowing illegal copies of digital contents. Among digital contents, watermarking technique can be used to protect ownership about the image. Copyright protection involves the authentication of image ownership and the identification of illegal copies of image. In this paper, a new digital watermarking technique using HVS and adaptive scale factor based on the wavelet transform is proposed to use the binary image watermark. The original image is decomposed by 3-level wavelet transform. It is embedded to baseband and high frequency band. The embedding in the baseband is considered robustness, the embedding in the high frequency band is concerned about HVS and invisibility. The watermarking of a visually recognizable binary image used the HVS and random permutation to protect the copyright. From the experimental results, we confirm that the proposed technique is strong to various attacks such as joint photographic experts ground(JPEG) compression, cropping, collusion, and inversion of lines.

• Journal of Ubiquitous Convergence Technology
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• v.2 no.1
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• pp.18-26
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• 2008

The invariance relation existing in the non-negative matrix factorization (NMF) is used for constructing robust image hashes in this work. The image is first re-scaled to a fixed size. Low-pass filtering is performed on the luminance component of the re-sized image to produce a normalized matrix. Entries in the normalized matrix are pseudo-randomly re-arranged under the control of a secret key to generate a secondary image. Non-negative matrix factorization is then performed on the secondary image. As the relation between most pairs of adjacent entries in the NMF's coefficient matrix is basically invariant to ordinary image processing, a coarse quantization scheme is devised to compress the extracted features contained in the coefficient matrix. The obtained binary elements are used to form the image hash after being scrambled based on another key. Similarity between hashes is measured by the Hamming distance. Experimental results show that the proposed scheme is robust against perceptually acceptable modifications to the image such as Gaussian filtering, moderate noise contamination, JPEG compression, re-scaling, and watermark embedding. Hashes of different images have very low collision probability. Tampering to local image areas can be detected by comparing the Hamming distance with a predetermined threshold, indicating the usefulness of the technique in digital forensics.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.466-469
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• 2000

In this paper, a watermarking technique for digital images is proposed. In our method, an image is 1-1eve1 wavelet transformed, and then the watermark of a binary stamp is embedded into the baseband. The watermark is embedded by inverting the polarities of the selected coefficient pairs. In the inverting process, we can increase perceptual image quality by finding means and differences of the selected neighboring coefficient pairs, and then adding values, which are inversely proportional to the differences, to the means. The experimental results show that the proposed method has good quality and is robust to JPEG lossy compression and various image processing operations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.598-601
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• 2002

In this research, robustness of image watermarking mixed Key and Logo scheme was evaluated. A personal ID of a copyrighter was key and watermark was logo image. The standard images of Baboon, Cameraman and Lena were used for experimental images, binary image‘Park’of 32$\times$32 and 64$\times$64 size were used for the watermark image, respectively. for robustness evaluation of the watermark, reconstructive rates of the watermark were obtained from images inserted watermark with image transformation or JPEG lossy compression. The experimental results show that the reconstructive rates of the case of 32$\times$32 watermark was better than the case of the 64$\times$64 watermark; average 5.9%, 13.9%, 6.5%, and 4.2% in the case of scale-down rates, rotational rates, impulse noise power density, and JPEG lossy compression rates, respectively.

• ETRI Journal
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• v.37 no.3
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• pp.595-605
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• 2015

This paper proposes a robust, imperceptible block-based digital video watermarking algorithm that makes use of the Speeded Up Robust Feature (SURF) technique. The SURF technique is used to extract the most important features of a video. A discrete multiwavelet transform (DMWT) domain in conjunction with a discrete cosine transform is used for embedding a watermark into feature blocks. The watermark used is a binary image. The proposed algorithm is further improved for robustness by an error-correction code to protect the watermark against bit errors. The same watermark is embedded temporally for every set of frames of an input video to improve the decoded watermark correlation. Extensive experimental results demonstrate that the proposed DMWT domain video watermarking using SURF features is robust against common image processing attacks, motion JPEG2000 compression, frame averaging, and frame swapping attacks. The quality of a watermarked video under the proposed algorithm is high, demonstrating the imperceptibility of an embedded watermark.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.5
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• pp.390-399
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• 1988

A conventional BTC has the merit of real time processing and simple computation, but has the problem that its compression rate is low. In this paper, a modified BTC using the Quad Tree which is frequently used in binary image is proposed. The method results in the low compression rate by decreasing the total number of subblocks by mean of making the size of a subblock large in the small variation area of graty level and the size af a subblock small in the large variation area of gary level. For the effective transmission of bit plane, the Huffman run-lengh code for the large size of a subblock and the lookup table for tha small size of a subblock are used. The proposed BTC method show the result of coding 256 level image at the average data rate of about 0.8 bit/pixel.