A blind CDMA image watermarking scheme in wavelet domain

The paper proposes a blind spread spectrum watermarking scheme where watermark information is embedded redundantly in the multilevel wavelet coefficients of the cover image. It has been shown that for a given embedding distortion, data embedding in LL and HH bands offers higher resiliency through better spectrum spreading compared to LH and HL band embedding, although the security of the hidden data is better in the later case. High resiliency of the scheme is supported by the good visual quality of the watermark images extracted from the several distorted watermarked images. Data hiding capacity is increased using code division multiple access (CDMA) technique and the mutual information values for the different watermark images are able to detect the degree of distortion already occurred in the watermarked image.