Based on the two-dimensional logistic map and a single improved genetic operator, a new image encryption system is proposed. The original image is transformed into DNA sequences, a subdivision into blocks of size calculated by using the chaotic map, with the intention to apply a crossover between blocks chaotically selected from a chaotic control vectors. For the installation of a diffusion phase, a strong link is established between the block resulting from a crossing operation and the next original block. Hoping to considerably increase the impact of the avalanche effect and protect the system against any differential attack. Simulations performed on a large number of images of different size and formats ensure that our method is not subject to any known attacks.