Abstract:

In order to balance the collision between the robustness and the sensitivity tampering of the watermarking technology, a dual digital watermarking scheme which embeds robust watermarking and fragile watermarking into the carrier images is proposed. A scramble operation and encryption to watermarking images are first prosecuted.A spread spectrum technique is used in the encrypted watermarking. Then, we embed an encrypted spread spectrum watermark into the hybrid transform domain: the experiment first performs discrete wavelet transform and discrete cosine transform to the carrier image, and then embeds the  watermarking message by changing part of each block DCT coefficient .The receiver realizes blind watermarking extraction. The experimental results show that this algorithm possesses better secrecy and invisibility, and has good robustness to noise and cropping attacks.

Key words: hybrid transform;dual marking;spread spectrum;blind watermarking