Visual cryptography for general access structures
Information and Computation
Constructions and Properties of k out of nVisual Secret Sharing Schemes
Designs, Codes and Cryptography
Extended capabilities for visual cryptography
Theoretical Computer Science
Improved Schemes for Visual Cryptography
Designs, Codes and Cryptography
Contrast Optimal Threshold Visual Cryptography Schemes
SIAM Journal on Discrete Mathematics
Contrast-Optimal k out of n Secret Sharing Schemes in Visual Cryptography
COCOON '97 Proceedings of the Third Annual International Conference on Computing and Combinatorics
A General Formula of the (t, n)-Threshold Visual Secret Sharing Scheme
ASIACRYPT '02 Proceedings of the 8th International Conference on the Theory and Application of Cryptology and Information Security: Advances in Cryptology
New visual secret sharing schemes using probabilistic method
Pattern Recognition Letters
Ideal contrast visual cryptography schemes with reversing
Information Processing Letters
Aspect ratio invariant visual secret sharing schemes with minimum pixel expansion
Pattern Recognition Letters
A cost-effective encryption scheme for color images
Real-Time Imaging - Special issue on multi-dimensional image processing
Designs, Codes and Cryptography
Efficient visual secret sharing scheme for color images
Pattern Recognition
Colored visual cryptography without color darkening
Theoretical Computer Science
Integrated Computer-Aided Engineering
Image Communication
Colored visual cryptography scheme based on additive color mixing
Pattern Recognition
On the security of a visual cryptography scheme for color images
Pattern Recognition
Image encryption by multiple random grids
Pattern Recognition
Ideal contrast visual cryptography schemes with reversing
Information Processing Letters
A new definition of the contrast of visual cryptography scheme
Information Processing Letters
Combinatorial Designs for Authentication and Secrecy Codes
Foundations and Trends in Communications and Information Theory
Image secret sharing method with two-decoding-options: Lossless recovery and previewing capability
Image and Vision Computing
Using colors to improve visual cryptography for black and white images
ICITS'11 Proceedings of the 5th international conference on Information theoretic security
ICIAR'06 Proceedings of the Third international conference on Image Analysis and Recognition - Volume Part I
New size-reduced visual secret sharing schemes with half reduction of shadow size
ICCSA'05 Proceedings of the 2005 international conference on Computational Science and its Applications - Volume Part I
Colored visual cryptography without color darkening
SCN'04 Proceedings of the 4th international conference on Security in Communication Networks
Extended visual secret sharing schemes with high-quality shadow images using gray sub pixels
ICIAR'05 Proceedings of the Second international conference on Image Analysis and Recognition
Compatible ideal contrast visual cryptography schemes with reversing
ISC'05 Proceedings of the 8th international conference on Information Security
Improvements of a two-in-one image secret sharing scheme based on gray mixing model
Journal of Visual Communication and Image Representation
Real perfect contrast visual secret sharing schemes with reversing
ACNS'06 Proceedings of the 4th international conference on Applied Cryptography and Network Security
Color visual cryptography schemes for black and white secret images
Theoretical Computer Science
Improved tagged visual cryptography by random grids
Signal Processing
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In 1994, Naor and Shamir introduced an unconditionally secure method for encoding black and white images. This method, known as a threshold visual cryptography scheme (VCS), has the benefit of requiring no cryptographic computation on the part of the decoders. In a (k, n)-VCS, a share, in the form of a transparency, is given to n users. Any k users can recover the secret simply by stacking transparencies, but k-1 users can gain no information about the secret whatsoever.In this paper, we first explore the issue of contrast, by demonstrating that the current definitions are inadequate, and by providing an alternative definition. This new definition motivates an examination of minimizing pixel expansion subject to fixing the VCS parameters h and l. New bounds on pixel expansion are introduced, and connections between these bounds are examined. The best bound presented is tighter than any previous bound. An analysis of connections between (2, n) schemes and designs such as BIBD's, PBD's, and (r, λ)-designs is performed. Also, an integer linear program is provided whose solution exactly determines the minimum pixel expansion of a (2, n)-VCS with specified h and l.