Image watermarking algorithm applying CDMA

In this paper, we propose a DWT-based image-watermarking algorithm applying DS-CDMA. The improved orthogonal Gold sequences sets generated via m-sequences are used to spread spectrum of the watermark. The CDMA encoded watermark is embedded into the DWT domain by modulating selected DWT coefficients of the image in a fashion similar to CDMA. Blind recovery of the embedded data is achieved by analyzing the DWT coefficients of the watermarked image and the auto-correlation of orthogonal codes. The proposed algorithm is compared with the existing watermarking schemes based on CDMA. The experimental results demonstrate that the watermark with the proposed algorithm is robust to JPEG compression, Gaussian noise and other typical attacks.