DCT-Based Robust Watermarking with Swarm Intelligence Concepts

Digital watermarking, in conjunction with cryptography, is one of the two major categories for information security. Unlike cryptography that the encrypted information represents like noisy patterns, by using watermarking, the watermarked contents look almost identical to its original counterpart, while it still retains the capability to counteract intentional signal processing by others and keeps the existence of the hidden watermark. From this point of view, watermarking is suitable for covert communication since it tends not to cause the suspicion by others. Besides, there must be requirements to keep both the embedded watermark alive and the watermarked contents acceptable. In this paper, we make use of a technique for swarm intelligence, named bacterial foraging, for obtaining an optimized watermarking algorithm with a properly designed fitness function comprising the possible requirements including the watermarked image quality and the capability for the existence of extracted watermark. With our integration, simulation results demonstrate the advantages and effectiveness of the proposed algorithm.