Visual Cryptography: A Review

In today’s world handling and security of information from attacks becomes very important aspect for the individuals. Researchers are innovating new techniques to secure the information from unwanted intrusions. Various cryptography techniques are discovered and many are yet to be revealed. Here in this paper we are going to review an advanced method of information hiding i.e. Visual Cryptography. Visual Cryptography emerged as a special encryption technique for information hiding using images. In way that encrypted image can be decrypted by the human vision if the correct image key is used. By this cryptographic technique we can encrypt visual information (pictures, text, etc.) in a way that human visual system can perform decryption of encrypted information & no aid of computers needed. In visual cryptography a secret image is transformed into several share images. These share images are meaningful but noisy or distorted images. Combination of these share images can reveal the original secret image. This paper reviews two methods for visual cryptography of color images based on Shamir encryption method variants of k-out-of-n i.e.2-out-of-2, 2-out-of-n, n-out-of-n, and k-out-ofn scheme encryption method.