Image watermarking algorithm based on the code division multiple access technique

A multiple watermarking algorithm based on the Code Division Multiple Access (CDMA) spread spectrum technique is presented. Multiple copyright identifiers are convolutional encoded and block interleaved, and the orthogonal Cold sequences are used to spread spectrum of the copyright messages. The CDMA encoded copyright messages are embedded into the wavelet sub-bands. As a blind watermarking algorithm, the copyright identifiers are extracted without the original image. The experimental results show that the proposed algorithm improves the detection BER, and the multiple copyright identifiers have preferable robustness and invisibility.