Embedding data in digital images using CDMA techniques

A watermarking technique is proposed for embedding a significant amount of data in digital still images while retaining a high perceptual quality. The scheme employs digital communication techniques to achieve high robustness to standard image processing operations. Information is embedded in the frequency domain by modulating selected DFT values of the image and using sets of orthogonal codes in a fashion similar to CDMA. DFT values are grouped into different bands defining independent channels for carrying data. Blind recovery of the embedded data is achieved by analyzing the DFT values of the watermarked image. The performance of the proposed adaptive scheme is evaluated by computer simulations