Probabilistic color visual cryptography schemes for black and white secret images

摘要

Color-black-and-white visual cryptography scheme (CBW-VCS) is a methodology that utilizes colors to alleviate the pixel expansion problem. In a general (k, n) CBW-VCS, when k and n become larger, the pixel expansion increases dramatically. In this paper, two constructions for constituting a (k, n) threshold probabilistic CBW-VCS (PCBW-VCS) are introduced, where the generated color shares are non-expansible. The two proposed constructions are proven to be valid constructions which satisfy the security and contrast conditions. Theoretical analysis and sufficient experiments are demonstrated to shown the effectiveness and advantages of the proposed PCBW-VCSs. (C) 2020 Elsevier Inc. All rights reserved.