The ever advancement in technology and revolution in image processing augmented the need of transmission of secure images. Cryptography plays crucial role in providing security. In rapidly growing internetwork era safe and secure transfer of data is major issue of concern. Most of the data being transferred consists of images. Cryptography is one of the methods that ensure Security. Advanced Encryption Standard (AES) is a specification for the encryption of electronic data. It has been adopted by the U.S. government and is now used worldwide. Modified AES is proposed in this paper which is useful for applications like GIS.