A novel approach to digital watermarking, exploiting colour spaces

Abstract

Watermarking is the process of embedding information in a carrier in order to protect the ownership of text, music, video and images, while steganography is the art of hiding information. Normally watermarks are embedded in images but remain visible in the majority of commercial image databases, such as Getty (gettyimages.ie) or iStock Photo (istockphoto.com). Watermarked images display ownership information in the form of copyright notices super-imposed on the image itself. However this leaves traditional watermarking techniques vulnerable to tampering. Thus the advantage of using steganographic techniques for watermarking is that the watermark is resistant to detection and consequently to tampering. Robustness is a characteristic of critical importance, in order that a watermark is to survive image manipulation and enhancement processes, as well as intentional attacks, to ensure piracy is prevented. A review of digital image-based steganography and watermarking techniques is carried out in this document. This investigation reveals that most watermarking algorithms demonstrate partial resistance to attacks. The aim of this work is to produce a novel hybrid digital watermarking technique, based on the exploitation of both the RGB and the YCbCr colour spaces, using spatial domain techniques. A text watermark is embedded in the YCbCr colour space, while an image watermark is embedded in the RGB colour space. Results demonstrate that the proposed hybrid technique can withstand levels of geometric attacks and processing attacks up to a point where the commercial value of the images tested would be lost. Results also demonstrate technical and performance improvements over existing methods, in terms of security and algorithm e_ciency, while taking inspiration from steganography, to avoid drawing attention to the fact that an image contains hidden information.