Color Image Copyright Protection Digital Watermarking Algorithm Based on DWT & DCT

This paper combines the visual characteristics of low frequency sub-image of DWT and the ability of DCT to remove correlation between DWT coefficients. By doing this, this paper improves a blind DCT watermarking algorithm to get a new color image digital watermarking schema based on DWT and DCT. The schema applies a self-adapted color component choosing strategy; Preprocesses the watermark by Logistic chaotic encryption; Applies the DCT to low frequency sub-image of DWT to get rid of coefficient correlation; In addition to that this schema extract strategy is blind by using sub-sampling technique. According to simulation results, this watermarking schema is robust under common attacks especially the compression attacks.