A print and scan optimized watermarking scheme

We are present an algorithm for watermarking digital images with the aim of obtaining a very high quality of the watermarked image and a strong resistance to print and scan processes. We propose a method which combines an additive watermarking algorithm in the spatial domain providing resistance against cropping and exhaustive search and a synchronisation template in the Fourier domain providing resistance against geometrical deformations. The additive watermark in the spatial domain is based on an original generalized 2-D cyclic patterns for secret message embedding. The cyclic property and pattern redundancy facilitate detection and synchronisation against cropping and image processing basic attacks (like compression, filtering, blurring). This algorithm has to be complemented by a template insertion for providing resistance against rotation and scaling which are caused by the print and scan processes. We generate the template in the Fourier domain inserting some points locally. The watermark and the template are weighted by a human visual masking function. The global scheme, though very classical in its global concept, provides very efficient protection to a digital image which could be delivered both in a digital high quality format and in a printed form.