ISSN : 1796-2048
Volume : 4    Issue : 3    Date : June 2009

A Novel Ideal Contrast Visual Secret Sharing Scheme with Reversing
Haibo Zhang, Xiaofei Wang, and Youpeng Huang
Page(s): 104-111
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In visual secret sharing (VSS) schemes, a secret image can be visually revealed from overlapping
shadow images without additional computations. However, the contrast of reconstructed image is
much lost. Employing reversing operation to reverse black and white pixels as well as increasing
encoding runs is an effective way to improve the contrast. A novel VSS scheme with reversing is
presented in this paper. It achieves really ideal contrast within only [m/h] encoding runs (where m
and h are the number of the total columns and the number of the wholewhite columns in the basis
matrix to encode white pixels, respectively) and no pixel expansion occurs. It encodes the secret
image block by block. A block consists of m pixels, which means that m pixels together join into
each encoding step. It is suitable for all access structures and can be applied to encrypt
black-white, gray-scale and chromatic images. The experimental results, analyses and
comparisons show that the proposed scheme is optimal among those schemes with reversing in
encoding runs, pixel expansion, complexity, system capacity and encoding efficiency.

Index Terms
Visual secret sharing (VSS), reversing, ideal contrast