Impact of Error Filters on Shares in Halftone Visual Cryptography
Sunil Agrawal · 2012
Visual cryptography encodes a secret binary image (SI) into shares of random binary patterns.If the shares are xeroxed onto transparencies, the secret image can be visually decoded by superimposing a qualified subset of transparencies, but no secret information can be obtained from the superposition of a forbidden subset.The binary patterns of the shares, however, have no visual meaning and hinder the objectives of visual cryptography.Halftone visual cryptography encodes a secret binary image into n halftone shares (images) carrying significant visual information.When secrecy is important factor rather than the quality of recovered image the shares must be of better visual quality.Different filters such as Floyd-Steinberg, Jarvis, Stuki, Burkes, Sierra, and Stevenson's-Arce are used and their impact on visual quality of shares is seen.The simulation shows that error filters used in error diffusion lays a great impact on the visual quality of the shares.