Achieving Optimal Contrast in Visual Cryptography Schemes without Pixel Expansion
Thomas Monoth, Babu Anto P. · 2009
Abstract — In this paper we present visual cryptography scheme to encode a black and white image into the same size shares as the secret image. In addition, an improved method for the generation of shares is proposed using additional matrix. Visual cryptography method for encrypting printed texts, handwritten notes, and pictures are done in a perfectly secure way, and decoding these data with the human visual system. The contrast is the most important parameter in visual cryptography. Usually, the reconstructed secret image will be darker than the background of the original secret image. The proposed scheme achieves better contrast and reduces the noise in the reconstructed secret image without adding any computational complexity. In this technique the number of white pixels in the reconstructed secret image can be