In this paper, a new method is proposed for image encryption based on a chaotic maps. Replacing the image pixels and changing the gray level values used simultaneously. First, a chaotic logistic map system used to shuffling pixels then the gray level values changed using same orbit. Initial condition of the system choosed using a 80 bit secret key. Experimental results show that the method is resistive via common attacks. The entropy obtained from this method is 7.9975 that is very close to 8 a ideal value.