A contrast-sensitive reversible visible image watermarking technique

A reversible (also called lossless, distortion-free, or invertible) visible watermarking scheme is proposed to satisfy the applications, in which the visible watermark is expected to combat copyright piracy but can be removed to losslessly recover the original image. We transparently reveal the watermark image by overlapping it on a user-specified region of the host image through adaptively adjusting the pixel values beneath the watermark, depending on the human visual system-based scaling factors. In order to achieve reversibility, a reconstruction/ recovery packet, which is utilized to restore the watermarked area, is reversibly inserted into non-visibly-watermarked region. The packet is established according to the difference image between the original image and its approximate version instead of its visibly watermarked version so as to alleviate its overhead. For the generation of the approximation, we develop a simple prediction technique that makes use of the unaltered neighboring pixels as auxiliary information. The recovery packet is uniquely encoded before hiding so that the original watermark pattern can be reconstructed based on the encoded packet. In this way, the image recovery process is carried out without needing the availability of the watermark. In addition, our method adopts data compression for further reduction in the recovery packet size and improvement in embedding capacity. The experimental results demonstrate the superiority of the proposed scheme compared to the existing methods

Reversible Image Watermarking Using Modified Quadratic Difference Expansion and Hybrid Optimization Technique

With increasing copyright violation cases, watermarking of digital images is a very popular solution for securing online media content. Since some sensitive applications require image recovery after watermark extraction, reversible watermarking is widely preferred. This article introduces a Modified Quadratic Difference Expansion (MQDE) and fractal encryption-based reversible watermarking for securing the copyrights of images. First, fractal encryption is applied to watermarks using Tromino's L-shaped theorem to improve security. In addition, Cuckoo Search-Grey Wolf Optimization (CSGWO) is enforced on the cover image to optimize block allocation for inserting an encrypted watermark such that it greatly increases its invisibility. While the developed MQDE technique helps to improve coverage and visual quality, the novel data-driven distortion control unit ensures optimal performance. The suggested approach provides the highest level of protection when retrieving the secret image and original cover image without losing the essential information, apart from improving transparency and capacity without much tradeoff. The simulation results of this approach are superior to existing methods in terms of embedding capacity. With an average PSNR of 67 dB, the method shows good imperceptibility in comparison to other schemes

Difference-Expansion Based Reversible and Visible Image Watermarking Scheme

[[conferencetype]]國內[[conferencedate]]20150817~20150819[[booktype]]電子版[[iscallforpapers]]Y[[conferencelocation]]JiaoSi, Taiwa

A Reversible Image Watermarking Scheme with High Contrast Visible Watermarks

[[abstract]]A reversible image watermarking scheme recovers the original host image when extracting the embedded watermarks. General reversible image watermarking scheme embeds invisible watermarks. This paper presents a reversible image watermarking scheme with embedding highly contrast visible watermarks. The host image first segments to non-overlapped blocks. Each block then uses two watermarking schemes including difference-expansion based invisible watermarking and high-contrast visible watermarking to embed one watermark bit into the host image. The difference-expansion based invisible watermarking scheme is adopted for extracting the watermark bit. Some extra information is therefore needed to be recorded. The high contrast visible watermarking scheme embeds significant visible watermarks. Experimental results show that the proposed scheme embeds high contrast visible watermarks and the watermarks can be extracted perfectly.[[notice]]補正完