An improved hyper-chaotic system based on the hyper-chaos generated from Chen's system is presented,and some basic dynamical properties of the system are investigated by means of Lyapunov exponent spectrum,bifurcation diagrams and characteristic equation roots.Simulations show that the new improved system evolves into hyper-chaotic,chaotic,various quasi-periodic or periodic orbits when one parameter of the system is fixed to be a certain value while the other one is variable.Some computer simulations and bifurcation analyses are given to testify the findings.
In this paper,a novel zero-watermark copyright authentication scheme based on Internet public certification system is proposed.This approach utilizes Haar integer wavelet transform based on a lifting scheme and adaptive Harris corner detection to extract image features,which will be used to produce a binary feature map,and the map is very crucial to the generation of watermark registered later.By properly choosing the parameters of aforementioned techniques such as the threshold T and the radius of local feature region R,the feature map is so much more stable and distinguishing that it can be used to construct robust watermark.Simulations demonstrate that the proposed scheme is resistant to many kinds of signal processing and malicious attacks such as Gaussian blurring,additive noising,JPEG lossy compression,cropping,scaling and slight rotation operation.Compared with a relative scheme such as that of Chang's,the scheme in this paper is more practicable and reliable and can be applied to the area of copyright protection.
