Hybrid Image Watermarking Using Local Complexity Variations

Watermarking is a method for protection of digital media intellectual property. Production of multimedia content has increased in recent years and protection of copyright is highly demanded. Different watermarking methods have been proposed to satisfy the tradeoff between imperceptibility while maintaining a proper capacity for the embedded data. In general, transform domain watermarks, such as Contourlet-based methods, produce superior results as compared to spatial algorithms. Embedding in visually more complex regions of image would enhance imperceptibility of the method. In this paper we introduce a new complexity measure for this purpose. To show the effective of this criterion, we proposed a hybrid embedding scheme based on Contourlet Transform (CT) and Discrete Cosine Transform (DCT). This is done by analyzing complexities of image blocks in the CT domain to adaptively change the watermarking strength factor. This property enables our method to take advantage of all image blocks to elevate the embedding capacity while preserving imperceptibility. Experimental results show the efficiency of the proposed method to be higher than similar works in this domain.