title: Image size invariant visual cryptography for general access structures subject to display quality constraints.
abstract: Conventional visual cryptography (VC) suffers from a pixel-expansion problem, or an uncontrollable display quality problem for recovered images, and lacks a general approach to construct visual secret sharing schemes for general access structures. We propose a general and systematic approach to address these issues without sophisticated codebook design. This approach can be used for binary secret images in non-computer-aided decryption environments. To avoid pixel expansion, we design a set of column vectors to encrypt secret pixels rather than using the conventional VC-based approach. We begin by formulating a mathematic model for the VC construction problem to find the column vectors for the optimal VC construction, after which we develop a simulated-annealing-based algorithm to solve the problem. The experimental results show that the display quality of the recovered image is superior to that of previous papers.
authors.affiliation: Department of Computer Science and Information Engineering, Ming Chuan University, Taoyuan, Taiwan. khlee@mail.mcu.edu.tw
authors.forename: Kai-Hui
authors.initials: KH
authors.lastname: Lee
authors.forename: Pei-Ling
authors.initials: PL
authors.lastname: Chiu