Visual Cryptography using Image Pixel Transparency

Abstract

This thesis makes use of transparency of pixels of the shares, the two or more encrypted images, so as to reveal the secret image. The pixels of shares can be generated randomly or the cover image can be used to generate the first share. The encrypted shares generated using cover image seem to be visually less similar to those generated without using cover image. Also, on the basis of image similarity between shares and original image, further encryption of encrypted shares can be performed. This thesis also compares the outcome when cover image is used and when not used to generate shares. Results show that the latter is more sensitive to the transparency factor (alpha) than the former encouraging the use of properly selected cover image for visual cryptography using pixel transparency.