With the increasing demand of providing security for images/videos with private information, chaos-based cryptosystems have played an important role in image encryption because of their excellent random properties and encryption performance. However, existing chaos-based systems have the security defect due to small key space or other security weakness. This paper introduces a new chaotic system using a combination of three conventional chaotic maps. The proposed chaotic system shows excellent chaotic behaviors. To demonstrate its application in image processing, a new image encryption scheme using the proposed chaotic system is also introduced. Computer simulation and security analysis demonstrate that the proposed image encryption scheme shows excellent encryption performance, high sensitivity to the security keys, and a sufficiently large key space to resist the brute attack. © 2012 IEEE.