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Proceedings of 2009 International Symposium on Computer Science and Computational Technology (ISCSCT 2009)

Huangshan, China, December 26-28, 2009

Editors: Fei Yu, Guangxue Yue, Jian Shu, Yun Liu

AP Catalog Number: AP-PROC-CS-09CN005

ISBN: 978-952-5726-07-7 (Print), 978-952-5726-08-4 (CD-ROM)

Page(s): 310-315

Threshold Visual Cryptography Scheme for Color Images with No Pixel Expansion

        Xiaoyu Wu, Duncan S.Wong, and Qing Li

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Since the introduction of threshold visual cryptography by Naor and Shamir, there have been many  other schemes proposed; some of them support color  images with a limited number of color  levels while a few others achieve the property of no pixel expansion.  However, it is unknown if there is a scheme which can satisfy all the following five commonly desired properties: (1) supporting images of arbitrary number of colors; (2) no pixel expansion; (3) no preprocessing of original images (e.g. dithering or block averaging); (4) supporting k-out-of-n threshold setting; and (5) a ‘tunable’ number of color levels in the secret share creation process. In this paper, we answer this question affirmatively by proposing a k-out-of-n threshold visual cryptography scheme which satisfies all these properties. In particular, our scheme uses a probabilistic technique for achieving no pixel expansion and generically converts any k-out-of-n threshold visual cryptography scheme for black-and-white images into one which supports color images.

Index Terms

Colored Visual Cryptography, Secret Sharing

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