Visual Cryptography for Digital Watermarking in Still Images

Abstract

Visual cryptograph can represent the secret image by several different shares of binary images. It is hard to perceive any clues about a secret image from individual shares. The secret message is revealed when parts or all of these shares are aligned and stacked together. In this paper, a novel public robust digital watermarking scheme based on visual cryptography is proposed. A binary logo is used to represent the ownership of the host image. The logo is used to generate a private sharing image and a public sharing image by visual cryptography algorithms. We use the public sharing image as the watermark embedded in the host image. An error correction-coding scheme is also used to protect the watermark. Simulation shows that our proposed watermarking algorithm is robust against various attacks indeed. Our algorithm and public share image can be open to the public, but only the owner, who uses the private sharing image of the ownership logo, can retrieve the logo for ownership. If there is an argument between the owner and the attacker the private sharing image can be provided to the arbitrator to resolve the ownership issue more convincingly.