Image Watermarking in Spatial Domain Using QIM and Genetic Algorithm

Digital watermarking is one of the proposed solutions for copyright protection of multimedia data. A watermark is a form of image or text that is impressed onto paper, which provides evidence of its authenticity. A digital watermark is digital data embedded in some host document so as to later prove the ownership of the document. Digital image watermarking refers to digital data embedding in images. Robust image watermarking systems are required so that watermarked images can resist geometric attacks in addition to common image processing tasks, such as JPEG compression. Least Significant Bit (LSB) watermarking, is one of the most traditional method of watermarking which changes the LSB of individual pixels in correlation with the watermark. However, pure LSB scheme provides a fragile watermarking technique which is not acceptable in practical applications. Also, robustness against geometric attacks, such as rotation, scaling and translation, still remains one of the most challenging research topics in pixel based image watermarking. In this paper, a new pixel-based watermarking system is proposed, in which a binary logo is embedded, a bit per pixel, in the pixel domain of an image. The LSB based watermarking is then quantized using QIM, augmented with genetic algorithm to produce a watermarking scheme which is highly robust against geometrical attacks.