Probabilistic Visual Secret Sharing Schemes for Gray-scale images and Color images

TL;DR

This paper introduces flexible probabilistic visual secret sharing schemes for gray-scale and color images that allow user-defined pixel expansion, including schemes with no pixel expansion, maintaining high image quality.

Contribution

It presents novel probabilistic (k, n)-VSS schemes for gray-scale and color images with adjustable pixel expansion, unifying and extending previous binary image schemes.

Findings

Pixel expansion can be set to any value, including zero.

Reconstructed images have quality comparable to existing deterministic schemes.

Previous binary schemes are special cases of the proposed methods.

Abstract

Visual secrete sharing (VSS) is an encryption technique that utilizes human visual system in the recovering of the secret image and it does not require any complex calculation. Pixel expansion has been a major issue of VSS schemes. A number of probabilistic VSS schemes with minimum pixel expansion have been proposed for binary secret images. This paper presents a general probabilistic (k, n)-VSS scheme for gray-scale images and another scheme for color images. With our schemes, the pixel expansion can be set to a user-defined value. When this value is 1, there is no pixel expansion at all. The quality of reconstructed secret images, measured by Average Relative Difference, is equivalent to Relative Difference of existing deterministic schemes. Previous probabilistic VSS schemes for black-and-white images with respect to pixel expansion can be viewed as special cases of the schemes proposed here