Visual Cryptography Scheme for Gray Scale Images based on Intensity Division

Broadly speaking a term Cryptography used to secure & hide the original information of a message from the unauthorised users. First time used to encrypt a plaintext into cipher text where a key was associated at the time of encryption to change original content into some other form i.e. decrypted message. And same key was used to decrypt that message into original form. In the modern communication era, people begin to transmit huge digital and multimedia information through the public network. During the transmission, most important thing is to secure data, for which a different kind of cryptography used, known as Visual Cryptography Scheme (VCS). This paper presents a new VCS approach & its implementation for gray scale images based on Intensity Division. In this approach the intensity of a pixel is divided into MSBs & LSBs. Two shares are generated using MSBs and at the receiver’s end stacking of these provide the revealed image. It also improves the quality of shared images even after decryption of the secret image. This is finally compared with the original Host image. Performance of this approach can be measured by calculating MSE & PSNR and Histogram.