Blind reliable invisible watermarking method in wavelet domain for face image watermark

In this paper, we have combined watermarking and biometrics for possible improvement in owner identification/verification technology. We have proposed and compared wavelet based four blind invisible watermarking methods that have used face image as watermark. Two watermarking methods are based on the discrete wavelet transform (DWT) and rest two watermarking methods are based on the redundant discrete wavelet transform (RDWT). One watermarking method in each transform incorporates weighted binary coding to achieve improved reliability of extracted watermark. Other watermarking methods replace original image coefficients with face image coefficients. We have observed that DWT based watermarking methods outperform RDWT based watermarking methods. We have compared the robustness of the proposed watermarking methods against various common image processing attacks/operations. We have observed that DWT based watermarking method coupled with weighted binary coding has the best performance without attacks; peak signal to noise ratio value of watermarked image is greater than 50 dB and normalized correlation coefficient value of extracted watermark is 1 at the watermark embedding strength of 1. Moreover, the same watermarking method has the best robustness against most of the attacks.