An adaptive spread spectrum watermarking algorithm based on orthogonal Walsh codes

This paper presents a Walsh code orthogonal spread spectrum watermarking algorithm. First, the watermark is modulated by two orthogonal Walsh codes. Then the watermark is embedded into the medium frequency and low frequency of the carrier block, according to the visual masking effect of the human visual system. The extraction of the watermark without the original image, using correlation detection to despreading. Experimental results show that the algorithm is robust variety of attacks.