Halftone Visual Cryptography for Grayscale Images Using Error Diffusion and Direct Binary Search

Visual Cryptography(VC) provides prefect security and the decoding is done without the help of a computer device. Halftone visual cryptography (HVC) uses halftoning techniques to produce shares, which maintains good contrast and security also increases the quality of shares. HVC increases the region of VC by the inclusion of digital halftoning technique. The problem of encoding and transmitting a secret message with high security is discussed and implemented by using meaningful halftone shares. Using Error diffusion or Direct binary search a secret message of a grayscale can be encoded into shares. Simulation results show several illustrative examples with its parameters.