fast planar oriented ripple search algorithm for hyperspace vq codebook this paper presents a fast codebook search method for improving the quantization complexity of full search vector quantization vq the proposed method is built on the planar voronoi diagram to label a ripple search domain then the appropriate codeword can easily be found just by searching the local region instead of global exploration in order to take a step further and obtain the close result full search vq would we equip the proposed method with a duplication mechanism that helps to bring down the possible quantizing distortion to its lowest level according to the experimental results the proposed method is indeed capable of providing better outcome at a faster quantization speed than the existing partial search methods moreover the proposed method only requires a little extra storage for duplication

blind source separation with nonlinear autocorrelation and non gaussianity blind source separation bss is a problem that is often encountered in many applications such as biomedical signal processing and analysis speech and image processing wireless telecommunication systems data mining sonar radar enhancement etc one often solves the bss problem by using the statistical properties of original sources e g non gaussianity or time structure information nevertheless real life mixtures are likely to contain both non gaussianity and time structure information sources rendering the algorithms using only one statistical property fail in this paper we address the bss problem when source signals have non gaussianity and temporal structure with nonlinear autocorrelation based on the two statistical characteristics of sources we develop an objective function maximizing the objective function we propose a gradient ascent source separation algorithm furthermore we give some mathematical properties for the algorithm computer simulations for sources with square temporal autocorrelation and non gaussianity illustrate the efficiency of the proposed approach

a novel image hiding scheme based on block difference to transmit a secret image securely by embedding it into a cover image without drawing the unintended observer s attention a novel image hiding scheme is proposed by exploring the block correlation between the cover image and the secret image the stego image quality can be greatly improved experimental results demonstrate that the stego image has a high peak signal to noise ratio and the stego image is almost the same as the cover image

high capacity image hiding scheme based on vector quantization a novel grayscale image hiding scheme that is capable of hiding multiple secret images into a host image of the same size is proposed in this paper the secret images to be hidden are first compressed by vector quantization with additional index compression process then the compressed secret images are encrypted and embedded into the least significant bits of the host pixels to provide good image quality of the stego image the modulus function and the image property are employed to hide the secret bits into the host pixels and determine the number of hidden bits in each host pixel respectively according to the results the proposed scheme provides a higher hiding capacity and a higher degree of security than that of the virtual image cryptosystem

fractal basin boundaries abstract basin boundaries for dynamical systems can be either smooth or fractal this paper investigates fractal basin boundaries one practical consequence of such boundaries is that they can lead to great difficulty in predicting to which attractor a system eventually goes the structure of fractal basin boundaries can be classified as being either locally connected or locally disconnected examples and discussion of both types of structures are given and it appears that fractal basin boundaries should be common in typical dynamical systems lyapunov numbers and the dimension for the measure generated by inverse orbits are also discussed

lyapunov exponents singularities and a riddling bifurcation there are few examples in dynamical systems theory which lend themselves to exact computations of macroscopic variables of interest one such variable is the lyapunov exponent which measures the average attraction of an invariant set this article presents a family of noninvertible transformations of the plane for which such computations are possible this model sheds additional insight into the notion of what it can mean for an attracting invariant set to have a riddled basin of attraction so03 i 9007 97 03805 2j

sharing secret images using shadow codebooks abstract a practical specific r n threshold scheme for secret digital images is proposed in this paper by this scheme we divide a secret digital image into n pieces and distribute them to n participants the secret digital image can be reconstructed when and only when r or more participants cooperate for it the time complexity of this proposed scheme is independent of the size of the secret image in this scheme the setup phase is bounded by i j r 1 2 2 module multiplications plus i j r 1 module additions where i j is the size of the codebook except the time needed for generating the codebook the reconstructing phase is bounded by o r log2 r this scheme also achieves perfect secrecy

a fixed point algorithm for blind source separation with nonlinear autocorrelation this paper addresses blind source separation bss problem when source signals have the temporal structure with nonlinear autocorrelation using the temporal characteristics of sources we develop an objective function based on the nonlinear autocorrelation of sources maximizing the objective function we propose a fixed point source separation algorithm furthermore we give some mathematical properties of the algorithm computer simulations for sources with square temporal autocorrelation and the real world applications in the analysis of the magnetoencephalographic recordings meg illustrate the efficiency of the proposed approach thus the presented bss algorithm which is based on the nonlinear measure of temporal autocorrelation provides a novel statistical property to perform bss

hiding data in images by simple lsb substitution in this paper a data hiding scheme by simple lsb substitution is proposed by applying an optimal pixel adjustment process to the stego image obtained by the simple lsb substitution method the image quality of the stego image can be greatly improved with low extra computational complexity the worst case mean square error between the stego image and the cover image is derived experimental results show that the stego image is visually indistinguishable from the original cover image the obtained results also show a significant improvement with respect to a previous work

riddled basins of the optimal states in learning dynamical systems abstract a new phenomenon called riddled basin has been drawing attention of nonlinear scientists riddled basin is an extremely complicated domain of attraction usually accompanying invariant sets for dynamical systems driven by chaotic signal e g chaotic synchronizing systems in this paper the optimal state of a back propagation learning of chaotic time series is shown to have a locally riddled basin by a numerical experiment it is also rigorously proved that the optimal state of learning of the tent map by a gradient descent method can be an attractor with a riddled basin

hybrid linear and nonlinear complexity pursuit for blind source separation blind source separation bss is an increasingly popular data analysis technique with many applications several methods for bss using the statistical properties of original sources have been proposed for a famous case non gaussianity this leads to independent component analysis ica in this paper we propose a hybrid bss method based on linear and nonlinear complexity pursuit which combines three statistical properties of source signals non gaussianity linear predictability and nonlinear predictability a gradient learning algorithm is presented by minimizing a loss function simulations verify the efficient implementation of the proposed method

a novel secret image sharing scheme in color images using small shadow images over the past several years secret image sharing techniques have become another branch of the effort to prevent secret images from being eavesdropped on in addition to traditional cryptography because smaller shadows can speed up the transmission of a secret color image in this paper we combine chang and wu s gradual search algorithm for a single bitmap btc gsbtc and shamir s k n threshold concept to propose a novel secret color image sharing scheme that generates smaller shadows experimental results confirm that the proposed scheme successfully reduces shadow size and that each shadow behaves as a random like image that prevents leakage of information about the secret color image furthermore the correlation between two vertically or horizontally adjacent pixels in each shadow is significantly less than those in a color secret image and the presented scheme also achieves on average an npcr 0 414 and auci 32 78 thus with our scheme one pixel difference could cause a significant difference in the corresponding shadows therefore the security of the presented scheme is also confirmed

interaction between discontinuity and non invertibility in a relaxation oscillator abstract a sinusoidally driven relaxation oscillator is studied by investigating the underlying one dimensional phase dynamics the map turns out to be a combination of conventional and inverse circle maps showing different types of supercritical behaviour the critical lines in the parameter space that correspond to the parameter values where the map becomes non invertible or discontinuous are obtained analytically between these critical lines the system shows either chaos if the map is non invertible or complete phase locking if the map is discontinuous above these two lines the mapping function is discontinuous as well as non invertible we report different mechanisms of the interaction between these two competing characteristics and the induced dynamical phenomena the general idea of these descriptions should be common for a large group of relaxation oscillators and their corresponding combined circle maps

a virtual image cryptosystem based upon vector quantization we propose a new image cryptosystem to protect image data it encrypts the original image into another virtual image since both original and virtual images are significant our new cryptosystem can confuse illegal users besides the camouflage this new cryptosystem has three other benefits first our cryptosystem is secure even if the illegal users know that our virtual image is a camouflage second this cryptosystem can compress image data finally our method is more efficient than a method that encrypts the entire image directly

fast and robust fixed point algorithms for independent component analysis independent component analysis ica is a statistical method for transforming an observed multidimensional random vector into components that are statistically as independent from each other as possible we use a combination of two different approaches for linear ica comon s information theoretic approach and the projection pursuit approach using maximum entropy approximations of differential entropy we introduce a family of new contrast functions for ica these contrast functions enable both the estimation of the whole decomposition by minimizing mutual information and estimation of individual independent components as projection pursuit directions the statistical properties of the estimators based on such contrast functions are analyzed under the assumption of the linear mixture model and it is shown how to choose contrast functions that are robust and or of minimum variance finally we introduce simple fixed point algorithms for practical optimization of the contrast functions

a multiple level visual secret sharing scheme without image size expansion in traditional vss schemes the size of the share image is substantially expanded since each pixel of the secret image is mapped onto a block consisting of several pixels in addition the quality of the reconstructed secret image is normally degraded in contrast especially for halftone images this study proposes a vss scheme that maps a block in a secret image onto one corresponding equal sized block in each share image without image size expansion two types of techniques including histogram width equalization and histogram depth equalization are proposed to generate the corresponding share blocks containing multiple levels rather than two levels based on the density of black pixels on the blocks for a secret block in the former technique the gray scale image histogram is obtained by uniformly splitting the range of the pixel gray levels in the secret image while in the latter the buckets are created so that the area of each bucket is roughly constant by containing approximately the same number of pixels the proposed schemes significantly improve the quality of the reconstructed secret image compared to several previous investigations

efficient visual secret sharing scheme for color images a k out of n visual secret sharing scheme vsss resolves the visual variant of the k out of n secret sharing problem where only k or more out of n participants can reveal the secret by human visual system without any cryptographic computation the best pixel expansion of the general k out of n vsss for c colored images was cxm by yang and laih new colored visual secret sharing schemes des codes cryptogr 24 2000 325 335 where m is the pixel expansion of an existing binary k out of n vsss regarding the c colored n out of n scheme the best pixel expansion is c 1 2 n 1 c 2 and c c 1 2 n 2 c when n is odd and even respectively by blundo et al improved schemes for visual cryptography des codes cryptogr 24 2001 255 278 in this paper we propose a new c colored k out of n vsss by using a pixel expansion of log 2c xm that is more efficient than ever

the transition to chaotic attractors with riddled basins abstract recently it has been shown that there are chaotic attractors whose basins are such that any point in the basin has pieces of another attractor basin arbitrarily nearby the basin is riddled with holes here we consider the dynamics near the transition to this situation as a parameter is varied using a simple analyzable model we obtain the characteristic behaviors near this transition numerical tests on a more typical system are consistent with the conjecture that these results are universal for the class of systems considered

color image steganography scheme using dft spiht codec and modified differential phase shift keying techniques abstract in this research on the basis of the differential phase shift keying dpsk technique which is widely used in digital communication systems to develop a steganography scheme we aim to hide a secret image into a cover image of the same size so that the resultant image has no noticeable degradation in our approach three strategies are used to achieve this goal 1 compress the secret image to reduce the number of secret bits the set partitioning in hierarchical trees spiht codec were used to obtain a high reconstructed image quality and low bit rate image compression 2 a neighbor block signal phase comparison nbspc mechanism is used to offer the location for secret data embedding 3 a fold phase distribution differential phase shift keying fpdpsk mechanism is used to improve the quality of the cover image with our contribution we have developed the fold phase distribution dpsk concept to obtain more than 1 5 db quality improvement and twice the noise margin than the standard dpsk technique on the same test condition

a two codebook combination and three phase block matching based image hiding scheme with high embedding capacity image hiding is a technique that embeds the important images into a cover image such that the important images are imperceptible and can be securely transmitted to the receiver in such research the common goals are to enlarge the embedding capacity as much as possible since the visual quality of the cover image is degraded slightly and to keep high visual quality of the important images when they are extracted from the stego image in this paper we propose an image hiding method based on the two codebook combination the three phase block matching procedure and the modulus substitution the proposed method can achieve these benefits 1 multiple relatively large important images can be embedded into a relatively small cover image 2 the quality of the stego image after embedding the secret data is not distorted significantly 3 the important images have an acceptable visual quality after they are extracted the experimental results also show that the proposed method is more flexible than previous methods

a new constrained fixed point algorithm for ordering independent components independent component analysis ica aims to recover a set of unknown mutually independent components ics from their observed mixtures without knowledge of the mixing coefficients in the classical ica model there exists ics indeterminacy on permutation and dilation constrained ica is one of methods for solving this problem through introducing constraints into the classical ica model in this paper we first present a new constrained ica model which composed of three parts a maximum likelihood criterion as an objective function statistical measures as inequality constraints and the normalization of demixing matrix as equality constraints next we incorporate the new fixed point newfp algorithm into this constrained ica model to construct a new constrained fixed point algorithm computation simulations on synthesized signals and speech signals demonstrate that this combination both can eliminate ics indeterminacy to a certain extent and can provide better performance moreover comparison results with the existing algorithm verify the efficiency of our new algorithm furthermore and show that it is more simple to implement than the existing algorithm due to its advantage of not using the learning rate finally this new algorithm is also applied for the real world fetal ecg data experiment results further indicate the efficiency of the new constrained fixed point algorithm

color image steganography scheme using set partitioning in hierarchical trees coding digital fourier transform and adaptive phase modulation in this research of color image hidden scheme we aim to conceal a secret image into the cover image of the same size without noticeable degradation in our approach discrete wavelet transform dwt and set partitioning in hierarchical trees spiht codec are used to obtain a low bit rate and high reconstructed quality image compression in the embedding process an adaptive phase modulation apm mechanism and discrete fourier transform dft were adopted for secret data embedding simultaneously nearest phase modulations npm was used to improve the imperceptibility and decrease degradation of cover image both the chaotic mechanism cm and frequency hopping fh structure were hired to enhance the security of the scheme comparing with other data hiding techniques our proposed method has three advantages a the extracted secret image has high quality reconstruction by using spiht coder b the stego image possesses excellent imperceptibility without noticeable degradation because secret data was concealed in the phase by using apm and npm c have very large embedding capacity it allows the size of secret image to be the same as the cover image

an image hiding method with high hiding capacity based on best block matching and k means clustering this paper presents a novel image hiding method that exhibits a high hiding capacity that allows the embedded important image to be larger than the cover image a facility that is seldom described in the literature in the proposed method the entire important image is divided into many nonoverlapping blocks for each block of the important image a block matching procedure is used to search for the best similar block from a series of numbered candidate blocks the obtained indices of the best matching blocks are encoded using huffman coding scheme and then recorded in the least significant bit planes of the cover image through a monoalphabetic transposition cipher the proposed method exhibits the following advantages over existing methods 1 a high hiding capacity such that the embedded important image can be larger than the cover image 2 a stego image with a high quality which improves the secrecy of the hidden image and 3 a small error between the extracted important image and the original important image indicating that the extracted important image is of acceptable quality

transverse instability and riddled basins in a system of two coupled logistic maps riddled basins denote a characteristic type of fractal domain of attraction that can arise when a chaotic motion is restricted to an invariant subspace of total phase space an example is the synchronized motion of two identical chaotic oscillators the paper examines the conditions for the appearance of such basins for a system of two symmetrically coupled logistic maps we determine the regions in parameter plane where the transverse lyapunov exponent is negative the bifurcation curves for the transverse destabilization of low periodic orbits embedded in the chaotic attractor are obtained and we follow the changes in the attractor and its basin of attraction when scanning across the riddling and blowout bifurcations it is shown that the appearance of transversely unstable orbits does not necessarily lead to an observable basin riddling and that the loss of weak stability when the transverse lyapunov exponent becomes positive does not necessarily destroy the basin of attraction instead the symmetry of the synchronized state may break and the attractor may spread into two dimensional phase space

riddled like basins of transient chaos the set of initial conditions leading to transient chaos in the neighborhood of a crisis is shown to display riddled like behavior for finite arbitrarily small accuracy calculations are performed with the logistic equation as well as with an experimentally verifiable quantitative description of a chemical reaction limitations in computational or experimental accuracy make the apparent riddling of initial conditions a phenomenon that is indistinguishable from riddled basins

basins of attraction in piecewise smooth hamiltonian systems piecewise smooth hamiltonian systems arise in physical and engineering applications for such a system typically an infinite number of quasiperiodic attractors coexist here we use the term attractors to indicate invariant sets to which typically initial conditions approach as a result of the piecewise smoothness of the underlying system these attractors are therefore characteristically different from the attractors in dissipative dynamical systems we find that the basins of attraction of different attractors exhibit a riddledlike feature in that they mix with each other on arbitrarily fine scales this practically prevents prediction of attractors from specific initial conditions and parameters the mechanism leading to the complicated basin structure is found to be characteristically different from those reported previously for similar basin structure in smooth dynamical systems we demonstrate the phenomenon using a class of electronic relaxation oscillators with voltage protection and provide a theoretical explanation

compression unimpaired batch image encryption combining vector quantization and index compression as the network bandwidth has grown rapidly it has become common to share a large number of still images via the internet by means of batch transmission unfortunately most existing methods encrypt only a single image so there is room for improvement in our ability to send batches of images at one time a complete reconstruction of the methods is sometimes necessary especially when considering performance criteria this paper presents a novel batch image encryption algorithm that combines vector quantization vq and additional index compression process to benefit from their computational efficiency and low transmission bandwidth without affecting the original compression rate the experimental results show the performance of this new scheme in terms of compression rate and computational cost

dynamics of a piecewise linear map with a gap in this paper we consider periodic solutions of discontinuous non smooth maps we show how the fixed points of a general piecewise linear map with a discontinuity a map with a gap behave under parameter variation we show in detail all the possible behaviours of period 1 and period 2 solutions for positive gaps we find that period 2 solutions can exist independently of period 1 solutions conversely for negative gaps period 1 and period 2 solutions can coexist higher periodic orbits can also exist and be stable and we give several examples of how these solutions behave under parameter variation finally we compare our results with those of jain banerjee jain banerjee 2003 int j bifurcat chaos 13 3341 3351 and banerjee et al banerjee et al 2004 ieee trans circ syst ii 51 649 654 and explain their numerical simulations

characteristics of a piecewise smooth area preserving map we are reporting a study carried out in a system concatenated by two area preserving maps the system can be viewed as a model of an electronic relaxation oscillator with over voltage protection we found that a border collision bifurcation may interrupt a period doubling bifurcation cascade and that some special features such as quasicoexisting periodic orbits crossing border as well as the transition between quasitransience and chaotic orbits accompany the process these features belong to the so called quasidissipative properties here quasitransience denotes the behavior of iterations outside elliptic islands they are attracted to the islands as soon as it reaches the islands the iteration follows the conservative regulations exactly this induces a kind of escaping from strange sets the scaling behavior of the escaping rate is obtained numerically

evolving decision tree rule based system for audio stego anomalies detection based on hausdorff distance statistics this work is motivated by the interest in forensics steganalysis which is aimed at detecting the presence of secret messages transmitted through a subliminal channel a critical part of the steganalyser design depends on the choice of stego sensitive features and an efficient machine learning paradigm the goals of this paper are 1 to demonstrate that the higher order statistics of hausdorff distance a dissimilarity metric offers potential discrimination ability for a clean and a stego audio and 2 to achieve promising classification accuracy by realizing the proposed steganalyser with evolving decision tree classifier stego sensitive feature selection process is imparted by the genetic algorithm ga component and the construction of the rule base is facilitated by the decision tree module the objective function is designed to maximize the precision and recall measures of the classifier thereby enhancing the detection accuracy of the system with low dimensional and informative features an extensive experimental evaluation of the proposed system on a database containing 4800 clean and stego audio files generated by using six different embedding schemes with the family of six ga decision trees was conducted the observations reported as 90 detection rate a promising score for a blind steganalyser show that the proposed scheme with the hausdorff distance statistics as features and the evolving decision tree as classifier is a state of the art steganalyser that outperforms many of the previous steganalytic methods

an invisible hybrid color image system using spread vector quantization neural networks with penalized fcm in this paper an invisible hybrid color image hiding scheme based on spread vector quantization vq neural network with penalized fuzzy c means pfcm clustering technology named spfnn is proposed the goal is to offer safe exchange of a color stego image in the internet in the proposed scheme the secret color image is first compressed by a spread unsupervised neural network with pfcm based on interpolative vq ivq then the block cipher data encryption standard des and the rivest shamir and adleman rsa algorithms are hired to provide the mechanism of a hybrid cryptosystem for secure communication and convenient environment in the internet in the spfnn the penalized fuzzy clustering technology is embedded in a two dimensional hopfield neural network in order to generate optimal solutions for ivq then we encrypted color ivq indices and sorted the codebooks of secret color image information and embedded them into the frequency domain of the cover color image by the hadamard transform ht our proposed method has two benefits comparing with other data hiding techniques one is the high security and convenience offered by the hybrid des and rsa cryptosystems to exchange color image data in the internet the other benefit is that excellent results can be obtained using our proposed color image compression scheme spfnn method