Improved Contrast for Threshold Random-grid-based Visual Cryptography

• Hao Hu,
• Gang Shen,
• Zhengxin Fu,
• Bin Yu,

Vol. 12, No. 7, July 30, 2018
10.3837/tiis.2018.07.022 , Download Paper (Free):

• Secret image sharing
• Visual cryptography
• random grid
• Threshold
• contrast

Abstract

Pixel expansion and contrast are two major performance parameters for visual cryptography scheme (VCS), which is a type of secret image sharing. Random Grid (RG) is an alternative approach to solve the pixel expansion problem. Chen and Tsao proposed the first (k, n) RGbased VCS, and then Guo et al., Wu et al., Shyu, and Yan et al. significantly improved the contrast in recent years. However, the investigations on improving the contrast of threshold RG-based VCS are not sufficient. In this paper, we develop a contrast-improved algorithm for (k, n) RG-based VCS. Theoretical analysis and experimental results demonstrate that the proposed algorithm outperformers the previous threshold algorithms with better visual quality and a higher accuracy of contrast.

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