Abstract:

To solve the problem of pixel expansion, a (2,3) visual cryptographic scheme without pixel expansion is proposed, in which the generated shares have the same size as the original image. Instead of considering one pixel of input image at a time, the proposed schemes consider 4 pixels at a time and generate 4 output pixels in each share. So the decrypted image remains the same size as the secret image. This technique generates shares with less space overhead compared to existing techniques and may provide better security. It is also easy to implement like other techniques of visual cryptography. The experiment results proved the efficiency of the proposed scheme.

Key words: visual cryptography, secret sharing, basic matrix, shares