Visual cryptography for general access structures
Information and Computation
Constructions and Properties of k out of nVisual Secret Sharing Schemes
Designs, Codes and Cryptography
New Colored Visual Secret Sharing Schemes
Designs, Codes and Cryptography
Extended capabilities for visual cryptography
Theoretical Computer Science
Contrast-optimal k out of n secret sharing schemes in visual cryptography
Theoretical Computer Science - computing and combinatorics
Threshold Visual Cryptography Schemes with Specified Whiteness Levels of Reconstructed Pixels
Designs, Codes and Cryptography
Improved Schemes for Visual Cryptography
Designs, Codes and Cryptography
Contrast Optimal Threshold Visual Cryptography Schemes
SIAM Journal on Discrete Mathematics
Optimal colored threshold visual cryptography schemes
Designs, Codes and Cryptography
A Matrix-Based Secret Sharing Scheme for Images
CIARP '08 Proceedings of the 13th Iberoamerican congress on Pattern Recognition: Progress in Pattern Recognition, Image Analysis and Applications
On the security of a visual cryptography scheme for color images
Pattern Recognition
On general construction for extended visual cryptography schemes
Pattern Recognition
A Secret Sharing Scheme for Digital Images Based on Cellular Automata and Boolean Functions
IWANN '09 Proceedings of the 10th International Work-Conference on Artificial Neural Networks: Part I: Bio-Inspired Systems: Computational and Ambient Intelligence
Image hiding based on circular geometric moiré
MATH'09 Proceedings of the 14th WSEAS International Conference on Applied mathematics
A secret sharing scheme for digital images based on two-dimensional linear cellular automata
IWCIA'08 Proceedings of the 12th international conference on Combinatorial image analysis
Image hiding based on circular moiré fringes
WSEAS Transactions on Mathematics
Image secret sharing method with two-decoding-options: Lossless recovery and previewing capability
Image and Vision Computing
A comprehensive study of visual cryptography
Transactions on data hiding and multimedia security V
Using colors to improve visual cryptography for black and white images
ICITS'11 Proceedings of the 5th international conference on Information theoretic security
Near-optimal time function for secure dynamic visual cryptography
ISVC'11 Proceedings of the 7th international conference on Advances in visual computing - Volume Part II
Improvements of a two-in-one image secret sharing scheme based on gray mixing model
Journal of Visual Communication and Image Representation
Robust approaches to 3d object secret sharing
ICIAR'10 Proceedings of the 7th international conference on Image Analysis and Recognition - Volume Part I
High-Entropy visual identification for touch screen devices
ISPEC'12 Proceedings of the 8th international conference on Information Security Practice and Experience
On the equivalence of two definitions of visual cryptography scheme
ISPEC'12 Proceedings of the 8th international conference on Information Security Practice and Experience
Improving the visual quality of random grid-based visual secret sharing
Signal Processing
Color visual cryptography schemes for black and white secret images
Theoretical Computer Science
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In a visual cryptography scheme a secret image is encoded into n shares, in the form of transparencies. The shares are then distributed to n participants. Qualified subsets of participants can recover the secret image by superimposing their transparencies. Non-qualified subsets of participants have no information about the secret image. In this paper we consider the case when the secret image is a colored image. Most of the previous work on colored visual cryptography allows the superposition of pixels having the same color assuming that the resulting pixel still has the same color. This is not what happens in reality since when superimposing two pixels of the same color one gets a darker version of that color, which effectively is a different color. Superimposing many pixels of the same color might result in a so dark version of the color that the resulting pixel might not be distinguishable from a black pixel. In this paper we propose a model where the reconstruction has to guarantee that the reconstructed secret pixel has the exact same color of the original one and not a darker version of it. We consider (k,n)-threshold schemes where a qualified set of participants consists of any k participants. We provide a general construction for any k, 2@?k@?n and a construction for the special case k=2. We also prove lower bounds on the pixel expansion (which is a measure of the goodness of the scheme) for the cases k=2 and k=n. The lower bounds match the pixel expansion of the schemes provided in these two cases, thus proving that our schemes are optimal with respect to the pixel expansion. We also provide an upper bound on the contrast of (k,n)-threshold schemes and (2,n)-threshold schemes with optimal contrast.