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Almost Ideal Contrast Visual Cryptography with Reversing
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Abstract: | A drawback of visual cryptography schemes (VCS) is much loss of contrast in the reconstructed image. This paper shows a new paradigm of VCS in which the original image is almost perfectly reconstructed. A very simple non-cryptographic operation is assumed, reversing black and white, which many copy machines have these days. We first show a $(k,n)$-VCS with {\it reversing} such that white pixels are almost perfectly reconstructed in addition to the perfect reconstruction of black pixels. The proposed scheme is fully compatible with traditional VCS in the following sense: Even if we do not have a copy machine as described above, we can reconstruct the secret image $I$ exactly in the same way as in the underlying VCS. In other words, we use a copy machine as a hedge to obtain better contrast. We next show how to convert a perfect {\it black} $(k,n)$-VCS (with reversing) into a perfect {\it white} $(k,n)$-VCS with reversing. Thirdly, we show a perfect black VCS for any monotone access structure. Finally, we show applications of our idea to colored VCS and grey level VCS, respectively. |
BibTeX
@misc{eprint-2004-12253, title={Almost Ideal Contrast Visual Cryptography with Reversing}, booktitle={IACR Eprint archive}, keywords={secret-key cryptography / visual cryptography, reversing, ideal contrast, perfect black}, url={http://eprint.iacr.org/2004/287}, note={A preliminary version of this paper was presented at CT-RSA 2004 and appeared in LNCS 2964 viet@nict.go.jp 12726 received 3 Nov 2004}, author={Duong Quang Viet and Kaoru Kurosawa}, year=2004 }