Hierarchical visual cryptography for grayscale image

In this technology era, every sensitive data must be secured. Visual cryptography is a technique to hide the image based secret. In visual cryptography the secret image is encrypted in to shares and at decryption side all shares are superimposed with each other so that secret is revealed. The key feature of visual cryptography is that, no difficult computation is needed at decryption side to decrypt the secret. In this paper we are applying Hierarchical Visual Cryptography Scheme on gray image instead of binary image. So, generated shares are gray share, not binary shares that are generated by the binary image. Here we are using the new proposed gray share generation algorithm for generation of n number of shares. Here original image is encrypted in to n number of levels so security of original image is increased. At decryption side all n shares must have to participate to reveal the original secret. Decrypted image has same size and better visual quality then original secret image.