Watermarking schemes to secure the face database and test images in a biometric system

This paper attempts to solve the integrity issues of a compromised face biometric system using two watermarking schemes. Two new blind watermarking schemes, namely S₁ and S₂, are proposed to ensure the integrity of the training face database and of the test images, respectively. Scheme S₁ is fragile spatial-domain based and scheme S₂ works in the discrete cosine transformation (DCT) domain and is robust to channel noise. The novelty of S₁ lies in the fact that it is lossless and the ratio of watermark bits to the size of the host image is 2.67, while S₂ has better robustness than existing blind watermarking schemes. The performance of both schemes is evaluated on a subset of the Indian face database and the results show that both schemes verify the integrity with very high accuracy without affecting the performance of the biometric system.