Digital watermarking is a technology to hide information in digital media. We extend the digital watermarking technique Phasemark™, originally developed solely for image authentication, to biometrics to assist in forensic analysis. Using a signature extracted from the Fourier phase of the original image, we hide an encoded signature back into the original image forming a watermarked image. The hiding occurs in the Fourier transform frequency domain. The detection process computes the Fourier transform of the watermarked images, extracts the embedded signature and then correlates it with a calculated signature. Various correlation metrics determine the identity degree of biometric authentication. We show how a composite filter can be used in conjunction with Phasemark™ for robust authentication of fingerprints.
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