Review on Color Image Encryption Algorithm based on Pseudorandom Number Key

In secure communication, image encryption schemes transform clear images into unintelligible others. The fundamental techniques used to encrypt a block of pixels are substitution and permutation. In recent years focuses on designing of highly robust encryption schemes (i.e., which provide good confusion and diffusion properties, to ensure desired security factor), either using peculiar pixel shuffling methods, or using innovative digital chaos-based ciphers, or by making justified compositions between these different pixel shuffling and ciphering techniques. Almost some encryption schemes based on permutation had already been found insecure against the cipher text-only and known/chosen-plaintext attacks, due to the high information redundancy, and it is quite understandable since the secret permutations can be recovered by comparing the plaintexts and the permuted cipher texts. Generally, chaos-based image encryption algorithms are used more often than others but require high computational cost. Moreover, a chaos system is defined on real numbers while the cryptosystems are defined on finite sets of integers. Furthermore, spatial domain scrambling has defect that the statistical characteristics of image are not changed after scrambling. Therefore, it is not secure to perform scrambling in spatial domain. The image encryption methods based on frequency domain encrypt/decrypt the images by modifying the image frequencies. One can recover the original plain image exactly via a reverse process

Recursive Procedural Tonal Art Maps

This paper presents a real-time procedural texturing algorithm for hatching parametrized surfaces. We expand on the concept of Tonal Art Maps to define recursive procedural tonal art maps that can service any required level-of- detail, allowing to zoom in on surfaces indefinitely. We explore the mathematical requirements arising for hatching placement and propose algorithms for the generation of the procedural models and for real-time texturing

Practical implementation of nonlinear time series methods: The TISEAN package

Nonlinear time series analysis is becoming a more and more reliable tool for the study of complicated dynamics from measurements. The concept of low-dimensional chaos has proven to be fruitful in the understanding of many complex phenomena despite the fact that very few natural systems have actually been found to be low dimensional deterministic in the sense of the theory. In order to evaluate the long term usefulness of the nonlinear time series approach as inspired by chaos theory, it will be important that the corresponding methods become more widely accessible. This paper, while not a proper review on nonlinear time series analysis, tries to make a contribution to this process by describing the actual implementation of the algorithms, and their proper usage. Most of the methods require the choice of certain parameters for each specific time series application. We will try to give guidance in this respect. The scope and selection of topics in this article, as well as the implementational choices that have been made, correspond to the contents of the software package TISEAN which is publicly available from http://www.mpipks-dresden.mpg.de/~tisean . In fact, this paper can be seen as an extended manual for the TISEAN programs. It fills the gap between the technical documentation and the existing literature, providing the necessary entry points for a more thorough study of the theoretical background.Comment: 27 pages, 21 figures, downloadable software at http://www.mpipks-dresden.mpg.de/~tisea