Details

Autor(en) / Beteiligte

• Wu, Xiaotian
• Fang, Jia
• Yan, Wei Qi

Titel

Contrast Optimization for Size Invariant Visual Cryptography Scheme

Ist Teil von

• IEEE transactions on image processing, 2023, Vol.32, p.2174-2189

Ort / Verlag

United States: IEEE

Erscheinungsjahr

2023

Quelle

IEEE Xplore

Beschreibungen/Notizen

• Visual cryptography scheme (VCS) serves as an effective tool in image security. Size-invariant VCS (SI-VCS) can solve the pixel expansion problem in traditional VCS. On the other hand, it is anticipated that the contrast of the recovered image in SI-VCS should be as high as possible. The investigation of contrast optimization for SI-VCS is carried out in this article. We develop an approach to optimize the contrast by stacking <inline-formula> <tex-math notation="LaTeX">t </tex-math></inline-formula> (<inline-formula> <tex-math notation="LaTeX">k \le t \le n </tex-math></inline-formula>) shadows in <inline-formula> <tex-math notation="LaTeX">(k, n) </tex-math></inline-formula>-SI-VCS. Generally, a contrast-maximizing problem is linked with a <inline-formula> <tex-math notation="LaTeX">(k, n) </tex-math></inline-formula>-SI-VCS, where the contrast by <inline-formula> <tex-math notation="LaTeX">t </tex-math></inline-formula> shadows is considered as an objective function. An ideal contrast by <inline-formula> <tex-math notation="LaTeX">t </tex-math></inline-formula> shadows can be produced by addressing this problem using linear programming. However, there exist <inline-formula> <tex-math notation="LaTeX">(n-k+1) </tex-math></inline-formula> different contrasts in a <inline-formula> <tex-math notation="LaTeX">(k, n) </tex-math></inline-formula> scheme. An optimization-based design is further introduced to provide multiple optimal contrasts. These <inline-formula> <tex-math notation="LaTeX">(n-k+1) </tex-math></inline-formula> different contrasts are regarded as objective functions and it is transformed into a multi-contrast-maximizing problem. The ideal point method and lexicographic method are adopted to address this problem. Additionally, if the Boolean XOR operation is used for secret recovery, a technique is also provided to offer multiple maximum contrasts. The effectiveness of the proposed schemes is verified by extensive experiments. Comparisons illustrate significant advancement on contrast is provided.