In this paper, a new self-adaptive image encryption algorithm is presented, which takes on a thorough integrity protect function and can be used in data validation. First, ergodic matrices are used to realize the position permutation algorithms. In particular, several novel methods of scrambling are proposed. By analysis of the weakness of pure position algorithms, a novel improved self-adaptive algorithm is proposed, which is strong under known-plaintext attack on image encryption. Finally the speed and safety of the new algorithm are analyzed and some simulation results are given.