An Improved Spread Spectrum Watermarking Technique to Withstand Geometric Deformations

The authors propose a new method for the watermarking to withstand the geometric attacks, which may occur during the transmission of the watermarked image. The underlying system is based on Direct Sequence Code Division Multiple Access (DS-CDMA). The algorithm for the normalization has been formulated for use in black and white images. The watermark is spread across the carrier image by using the pseudo-random noise sequences of optimal period and retrieval is made by the use of correlation. Private Key technique is used so the transmission is very secure. Matlab was used to implement the algorithm discussed here.