Almost-aspect-ratio-invariant visual cryptography without adding extra subpixels

作者：Yang Ching Nung^*; Lin Che Yu

来源：Information Sciences, 2015, 312: 131-151.

DOI：10.1016/j.ins.2015.03.024

• Visual secret sharing
• Visual cryptography
• Pixel expansion
• Aspect-ratio-invariant
• Almost-aspect-ratio-invariant

A visual cryptographic scheme is a method to decompose a secret image into shadow images by expanding a secret pixel into in subpixels. Only legitimate subsets of participants can reconstruct the original image by combining their shadows. Because the size of the subpixel is the same as that of the pixel, the shadow size is expanded m times. In cases where m is not a square number, the aspect ratio of the reconstructed image is distorted. Accordingly, an aspect ratio invariant VCS (ARIVCS) was proposed to address this distortion problem. However, ARIVCS requires extra subpixels and a mapping pattern showing how to arrange the subpixels. A large m creates a significant challenge when attempting to derive this pattern. In this paper, we propose the almost-aspect-ratio-invariant VCS (AAIVCS), which simulates the principle of a jigsaw puzzle. The proposed AAIVCS has the smallest loss of aspect ratio when we do not add extra subpixels.

• 出版日期2015-8-10
• 单位东华大学