Optical image watermarking using fractional Fourier transform

摘要

An optical image watermarking scheme using fractional Fourier transform is proposed. The watermark is encrypted using double random fractional order Fourier domain encoding scheme. Encrypted image is water marked into a host image. Embedding watermark sequences into fractional Fourier domain has an important advantage over embedding in spatial domain or in frequency domain. The watermark is recovered by applying corresponding correct fractional orders and random phase masks. The use of fractional Fourier transform offers additional degrees of freedom to enlarge the key size, thus enhancing the level of security. The effect of occlusion of watermarked image on the recovered watermark is also studied. The proposed idea is supported with simulation results.