A Weighted Threshold Visual Cryptography

Over the past years, a visual secret sharing scheme gave each share the same ability to reconstruct the secret image. That means each participant had the same significance to reveal the secret. However, it is not realistic in real world for some applications. In this paper, the weighted \( (k,n) \)-threshold visual cryptography scheme is proposed, in which the secret image is encoded into some shares with different weights and the sum of weights for all shares has to be equal to \( n \), according to the share-holders of different priority levels. In the decoding phase, when the shares with different weights are superimposed and the sum of weights of all stacking shares is equal to or larger than \( k \), the secret is then visually recognizable. Otherwise, no information about secret image is revealed. The proposed scheme is the first weighted \( (k,n) \)-threshold visual cryptography method with no pixel expansion. It is suitable for applications in the real life.

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