WATERMARKING TECHNIQUE FOR DIGITAL IMAGES (USING SVD)

Abstract

Digital watermarking addresses the growing concerns of theft and tampering of digital media through the use of advanced signal processing strategies to embed copyright and authentication information within media content., since it makes possible to identify the author, owner, distributor or authorized consumer of a document. In case of any dispute, one can prove their identity by decoding the watermark. This thesis aims to develop and implement Robust and secure watermarking technique for digital images. Two most important prerequisites for an efficient watermarking scheme are robustness and invisibility. After embedding the watermark, perceptual quality of the digital content should not be degraded and watermark must be recoverable from the watermarked image even if it is altered or processed by one or more image processing attacks such as compression, filtering, geometric distortions, resizing etc. In my research work, I have proposed a blind watermarking scheme based on the discrete wavelet transformation (DWT) and theory of linear algebra called “singular value decomposition (SVD)” to digital image watermarking..SVD method can transform A into product of USV, which allow us to refactoring a digital image in three matrixes. The using of singular values of such refactoring allows us to represent the image in the small set of values, which can preserve useful features of the original image, but use less storage space in the memory and achieve a image watermarking process. In this scheme, Singular Values (SV's) were embedded in the HH band of the watermark for perceptual transparency and robustness. Although the scheme proves to be robust however it is insecure. An authentication mechanism is proposed at the decoder for security enhancement. It is implemented by using a signature based authentication mechanism. Finally the resulting water- marking scheme is secure and robust.