In this paper we propose an image steganography technique which embeds secret data without making explicit modifications to the image. The proposed method simultaneously provides both imperceptibility and undetectability. We decompose image by contourlet transform and determine nonsmooth regions. Embedding data in these regions cause less degradation in image quality. Contourlet sub-bands are d...

In this paper a reversible data hiding scheme based on shifting the histogram of host image blocks is presented. This method attempts to use full available capacity for data embedding by dividing the image into non-overlapping blocks. Applying histogram shifting to each block requires that extra information to be saved as overhead data for each block. This extra information (overhead or bookkee...

The embedding dimension and the number of nearest neighbors are very important parameters in the prediction of a chaotic time series. In order to reduce the uncertainties in the determination of the forgoing two parameters, a new adaptive local linear prediction method is proposed in this study. In the new method, the embedding dimension and the number of nearest neighbors are combined as a par...

A secure method for steganography is proposed. Pixelvalue differencing (PVD) steganography and bit-plane complexity segmentation (BPCS) steganography have the weakness of generating blocky effects and noise in smooth areas and being detectable with steganalysis. To overcome these weaknesses, a secure bit-plane based steganography method on the spatial domain is presented, which uses a robust me...

This paper presents a block based spatial watermarking method. The main interest of this method is that it attempts to realise a good compromise between robustness performance, quality of the embedding and computational cost. This method is based on elementary perceptual criterion and adapts the embedding with regards to the content of the blocks. The paper ends with results deduced from many p...

Recently, video watermarking has become an important research issue due to increase in threats of video piracy, authentication, and ownership integrity. In this paper, we propose a new secure and robust watermarking method for H.264 compressed video stream with a blind extraction process. Most authors prefer embedding in I-frames because I-frames are crucial for video signal. However, the embed...

The idea of embedding a dynamical system, whose generator has both increasing and decreasing monotonicity properties (positive and negative feedback), into a larger symmetric monotone dynamical system and exploiting the convergence properties of the latter is very old. For a discussion of history of the method, see [4,8]. The method is repeatedly rediscovered and its implications are often unde...

ÐThis paper presents a block-based spatial watermarking method. The main interest of this method is that it attempts to realise a good compromise between robustness performance, quality of the embedding and computational cost. This method is based on elementary perceptual criterion and adapts the embedding with regards to the content of the blocks. The paper ends with results deduced from many ...

The Least Significant Bit (LSB) substitution is an old and simple data hiding method that could almost effortlessly be implemented in spatial or transform domain over any digital media. This method can be attacked by several steganalysis methods, because it detectably changes statistical and perceptual characteristics of the cover signal. A typical method for steganalysis of the LSB substitutio...

In network analysis, a community is typically considered of as a group of nodes with a great density of edges among themselves and a low density of edges relative to other network parts. Detecting a community structure is important in any network analysis task, especially for revealing patterns between specified nodes. There is a variety of approaches presented in the literature for overlapping...