Increasing the capturing angle in print-cam robust watermarking
Abstract It is nowadays more probable that a print media is captured and shared with a mobile phone than with a scanner. The reasons for photographing the print range from intention of copying the image to simply sharing an interesting add with friends. Watermarking offers a solution for carrying side information in the images, and if the watermarking method being used is robust to the print-cam process, the information can be read with a mobile phone camera. In this paper, we present a print-cam robust watermarking method that is also implemented on a mobile phone and evaluated with user tests. Especially, the lens focusing problem when the picture is captured in a wide angle with respect to the printout is addressed. The results show that the method is highly robust to capturing the watermark without errors in angles up to 60° with processing times that are acceptable for real-life applications.