Threshold visual secret sharing by random grids with improved contrast
We improve the contrast of Chen and Tsao's (k, n) threshold scheme published in The Journal of Systems and Software 84 (2011) 11971208. For (k, n) access structures satisfying k > n/2, the proposed scheme works the same way as Chen and Tsao's scheme. For (k, n) access structures satisfying k?n/2, the contrast of the proposed scheme is strictly larger than that of Chen and Tsao's scheme. Computer simulations for (2, 4) access structure show that our scheme outperforms Chen and Tsao's scheme significantly in visual quality.
random grids contrast visual cryptography