Watermark Visibility Adjustable RVW Scheme for JPEG Images

摘要

In digital images, visible watermarks are embedded to convey the ownership information directly to the world so that copyright violations can be prevented. The removable visible watermarking (RVW) techniques allow the authorized user to remove the watermark from the watermarked image and restore the host image with permissible loss. Usually the visibility of the watermark can't be increased or decreased based on the application requirement. In most of the commercial communication, JPEG images are used over the internet because of its reduced size. In this paper a RVW scheme is proposed for JPEG images which allows the user to embed watermark in the host image with variable visibility levels. In this scheme, the watermark embedding is performed by modifying the frequency coefficients of host image during forward Discrete Cosine Transform phase of JPEG compression. Inverse operation is performed to remove the watermark and to recover the host image. Watermark key is used to enhance the security of watermarking scheme. Quality metrics of visible watermarking technique are confirmed through experiments.