• Journal of Electrical Engineering and Technology
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• v.4 no.4
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• pp.552-558
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• 2009

We proposed a semi-blind digital image watermarking technique for copyright protection. The proposed algorithm embedded a binary sequence watermark into significant wavelet coefficients by using a quantization method. The main idea of the quantization method was to quantize a middle coefficient of the triplet of a significant wavelet coefficient according to the watermark's value. Unlike an existing algorithm, which used a random location table to find a coefficient in which the watermark bit will be embedded: the proposed algorithm used quad-tree decomposition to find a significant wavelet coefficient for embedding. For watermark detection, an original host image was not required. Thanks to the usage of significant wavelet coefficients, the proposed algorithm improved the correlation value, up to 0.43, in comparison with the existing algorithm.

• Journal of Internet Computing and Services
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• v.11 no.2
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• pp.99-107
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• 2010

In this paper a blind watermarking algorithm for digital image is presented. The proposed method operates in wavelet domain. The watermark is decomposed into 2D-IMFs using BEMD which is the 2-dimensional extension of 1 dimensional empirical mode decomposition. The CDMA based on SS technique is applied to watermark embedding and detection process. In the watermark embedding process, each IMF of watermark is embedded into middle frequency subimages in wavelet domain, so subimages just include partial information about embedded watermark. By characteristics of BEMD, when the partial information of watermark is synthesized, the original watermark is reconstructed. The experimental results show that the proposed watermarking algorithm is imperceptible and moreover is robust against JPEG compression, common image processing distortions.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3C
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• pp.256-268
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• 2007

In this paper, we present a watermarking method for 3-D mesh sequences. The main idea is to transform vertex norm with the identical connectivity index along temporal axis using wavelet transform and modify the distribution of wavelet coefficients in temporally high (or middle) frequency frames according to watermark bit to be embedded. All vertices are divided into groups, namely bin, using the distribution of coefficients in low frequency frames. As the vertices with the identical connectivity index over whole frames belong to one bin, their wavelet coefficients are also assigned into the same bin. Then, the watermark is embedded into the wavelet coefficients of vertex norm. Due to the use of the distribution, our method can retrieve the hidden watermark without any information about original mesh sequences in the process of watermark detection. Through simulations, we show that the proposed is flirty robust against various attacks that are probably concerned in copyright protection of 3-D mesh sequences.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.800-803
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• 2004

This paper presents a wavelet-based digital watermarking technique for still images. The digital watermarking considering human visual system (HVS) to increase the robustness and perceptual invisibility of digital watermark. The watermarking embedding is modified discrete wavelet transform (DWT) coefficients of the subbands of the images. The human visual system is number of factors that effect the noise sensitivity of human eyes that is considered to increase the robustness and perceptual invisibility of digital watermark. The watermark detection is blind watermark ( original image is not required ). Experimental results successful against attacks by image processing such as add noise, cropping, filtering, JPEG and JPEG2000 compression.

• Geosystem Engineering
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• v.21 no.5
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• pp.251-261
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• 2018

With the urbanization in recent years, the power line interference noise in electromagnetic signal is increasing day by day, and has gradually become an unavoidable component of noises in magnetotelluric signal detection. Therefore, a kind of power line interference noise elimination method based on independent component analysis in wavelet domain for magnetotelluric signal is put forward in this paper. The method first uses wavelet decomposition to change single-channel signal into multi-channel signal, and then takes advantage of blind source separation principle of independent component analysis to eliminate power line interference noise. There is no need to choose the layer number of wavelet decomposition and the wavelet base of wavelet decomposition according to the observed signal. On the treatment effect, it is better than the previous power line interference removal method based on independent component analysis. Through the de-noising processing to actual magnetotelluric measuring data, it is shown that this method makes both the apparent resistivity curve near 50 Hz and the phase curve near 50 Hz become smoother and steadier than before processing, i.e., it effectively eliminates the power line interference noise.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.2
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• pp.658-672
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• 2021

Since the signal with strong power need be demodulated first for successive interference cancellation (SIC) receiver in non-orthogonal multiple access (NOMA) systems, the base station (BS) need inform the near user terminal (UT), which has allocated higher power, of the far UT's modulation mode. To avoid unnecessary signaling overhead of control channel, a blind detection algorithm of NOMA signal modulation mode is designed in this paper. Taking the joint constellation density diagrams of NOMA signal as the detection features, the deep residual network is built for classification, so as to detect the modulation mode of NOMA signal. In view of the fact that the joint constellation diagrams are easily polluted by high intensity noise and lose their real distribution pattern, the wavelet denoising method is adopted to improve the quality of constellations. The simulation results represent that the proposed algorithm can achieve satisfactory detection accuracy in NOMA systems. In addition, the factors affecting the recognition performance are also verified and analyzed.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.11a
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• pp.520-522
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• 2014

Due to the availability of easy-to-use and powerful image editing tools, the authentication of digital images cannot be taken for granted and it gives rise to non-intrusive forgery detection problem because all imaging devices do not embed watermark. Forgery detection plays an important role in this case. In this paper, an effective framework for passive-blind method for copy-move image forgery detection is proposed, based on Gabor filter which is robust to illumination, rotation invariant, robust to scale. For the detection, the suspicious image is selected and Gabor wavelet is applied from whole scale space and whole direction space. We will extract the mean and the standard deviation as the texture features and feature vectors. Finally, a distance is calculated between two textures feature vectors to determine the forgery, and the decision will be made based on that result.

• Journal of Korea Multimedia Society
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• v.7 no.5
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• pp.744-754
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• 2004

In this paper, a polarity based blind watermarking method considering wavelet coefficients modification is proposed. In this proposed method, we use an asymmetric thresholds watermarking(ATW) in which detection threshold is higher than inserting threshold in order to enhance watermark detection ratio in attacked images. Also, in order to reduce errors in the detected value of watermarks according to small changes in the coefficient values when detecting watermarks, it set the range for movement variation of the coefficients and lowered the sensitivity of variation by ignoring the variations that fall into this range. For this purpose, the polarity preservation threshold $\beta$ was set and a watermark was detected based on the polarity only for the difference that was larger than $\beta$. The experimental results show that the proposed method has good quality and is robust to various attacks such as the JPEG lossy compression, noise addition, cropping, blurring, etc.

• Journal of Information Processing Systems
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• v.2 no.1
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• pp.13-17
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• 2006

In this paper, we propose an audio extraction method to decrease the influence of the original signal by modifying the watermarking detection system proposed by P. Bassia et al. In the extraction of the watermark, we employ a simple mean filter to remove the influence of the original signal as a preprocessing of extraction and the repetitive insertion of the watermark. As the result of the experiment, for which we used about 20 kinds of actual audio data, we obtain a watermark detection rate of about 95% and a good performance even after the various signal processing attacks.