Recently

a variety of encryption algorithms of digital image based on chaos theory have been studied

but a large part of them adopt the traditional confusion-diffusion architecture

the security of which is greatly reduced when attacked by selecting plain-image. In this paper

to address this problem

we propose a algorithm through changing the parameters of Arnold transform combined with Logistic mapping

which increases the correlationof the two operations. Simulation results and numerical analysis show that the algorithms has a large key space

be sensitive of secret keys

which can be effective to resist statistical attack.