Combined encryption and image compression using adaptive quadtree decomposition and coupled chaotic systems
Ranjan Bose, Saumitr Pathak · International Conference on Information and Automation · 2005
The proposed technique combines quadtree-based compression and chaotic-encryption, and can be used for secure image transmission over the internet. The method of quadtree decomposition, an image representation technique, essentially decomposes a given image into its four major quadrants, which are further decomposed progressively. The technique provides for a powerful variable resolution or variable block size image coding with potential for flexible and more efficient bit allocation than other fixed block size schemes. In the proposed technique, the quadtree decomposition is not regular but is varied adaptively according to a parameter of irregularity resulting in unequal block quadrant sizes. We have used the coupled chaotic system process for this purpose. We have compared the compression performance of our new scheme with regular decomposition and the two compare well. Thus, if the parameter of irregularity is incorporated into the key along with the tree structure of the image, then our algorithm transforms into a fast image encryption tool, providing medium to high level security for multimedia and internet applications.