Hiding biometric features in audio signals using Gram-Schmidt orthogonalisation

This paper presents a method of imperceptibly inserting a biometric-based digital watermark generated from iris image in an audio signal. The use of biometric features as a watermark is proposed in this paper to address the issue of ownership of digital watermark and digital content. There is a need to design special audio watermarking algorithm which can accommodate biometric-based watermark without disturbing robustness and perceptual transparency as biometric-based watermarks are generally larger in size. The algorithm is designed using Gram-Schmidt orthogonalisation in third level detailed coefficients of multi-resolution decomposition to achieve high payload with good robustness such that watermark is not audible to human auditory system. The embedding capacity of the proposed method is evaluated to be 480 bps and the highest SNR achieved is 41.519 dB. Experimental results validate that the biometric watermark extracted even under different attack situations can be identified uniquely in the iris database.