In this paper, an encryption technique using matrix based substitution and diffusion for fast image encoding is discussed. The cryptographic procedure manipulates a two dimensional array (matrix) for substitution and diffusion operations. The procedure facilitates fast conversion of plaintext and images into cipher text and cipher images. The paper describes the encryption procedure, discusses on performance and compares with Advanced Encryption Standard (AES). It is shown that the matrix based substitution and diffusion procedure is capable of encrypting images faster than advanced encryption standard.