Hi friend,
Visual cryptography encodes a secret binary image SI into n shares of random binary patterns. The secret image can be visually decoded by superimposing a qualified subset of shares, but no secret information can be obtained from the superposition of a forbidden subset. Such a scheme is mathematically secure, however, the binary patterns of the n shares have no visual meaning, raising the suspicion of data encryption. In order to achieve a higher level of security, halftone visual cryptography was proposed to encode a secret binary image into n halftone shares (images) carrying significant visual information.
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