Biometric watermarking using partial DCT-Walsh wavelet and SVD

Biometric has ever increasing demand in the field of security. However, integrity and security of biometric used to authenticate a legal user are the inherited problems of it. Since watermarking hides one form of digital data into other, its use in securing biometric data gives an added advantage. This concept has led to biometric watermarking technique in which one biometric can be embedded into another biometric feature of user to enhance security. In this paper a robust biometric watermarking technique using face images as host and iris images as watermark has been proposed with the combination of hybrid wavelet and Singular Value Decomposition. DCT-Walsh hybrid wavelet transform is used in its partial form (column transform) on host and watermark images. Low frequency coefficients of partially transformed hosts are subjected to SVD. Singular values of partially transformed watermark are adaptively scaled and are embedded in these singular values of host. Robustness of proposed technique is evaluated against compression, selective and random cropping, noise addition and resizing attack. Average absolute pixel difference between embedded and extracted watermark is used as similarity measure between them. Proposed technique is observed to be highly robust against these attacks except selective cropping. However this limitation is eliminated when iris images are embedded in middle frequency coefficients of host.