Abstract: Mobile platform has been widely used in our real life,such as smart phone,which causes the image security problem is becoming more and more prominent．It is extremely urgent to protect the image information security of smart phone．The image encryption technology by traditional computer platform has been be widely researched and applied,but the mobile platform is limited by the current hardware architecture,so that it can not inherit traditional security technology platform directly.Based on Android mobile platform,an image encryption scheme was put forward in this paper which aims at the image information security problems of smartphones and other mobile platforms．And the scheme is an innovation of the combination between gray level transformation and image method.Experiments show that the proposed scheme has higher efficiency in image encryption,which can effectively protect the security of image information in the mobile platform,and has extensive application value.

Key words: Mobile platform,Android,Image encryption