Improving Image Quality In Extended Visual Cryptography For Halftone Images With No Pixel Expansion

Abstract Visual cryptography is a secret sharing scheme that divides secret images into shares such that when the shares are superimposed a hidden secret image is revealed. In extended visual cryptography an extra security is provided by giving cover images to the shares. However in either case loss of resolution contrast and image size expansion are challenging problems that the researchers are facing. In this paper we propose a method for processing halftone images that improves the quality of the recovered images and also avoids pixel expansion. The resulting scheme maintains the perfect security of the original extended visual cryptography approach and also provides a better result.