共查询到16条相似文献,搜索用时 62 毫秒
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视觉密码(VC)是一种用于分享秘密图像的加密方案,与传统的密码技术相比具有简单性、安全性、隐蔽性等优点.其加密是将图像编码为分享,将分享打印在透明胶片上或以数字形式存储;其解密过程是对分享进行叠加,然后通过人类的视觉能力来实现.本文介绍了视觉密码的基本概念和各种不同的视觉密码方案,以及每种方案中使用的技术.此外,对视觉... 相似文献
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本文分析了基于小波变换的图像多分辨率压缩算法,通过对小波变换的特性和图像的分解特性进行分析,阐述了如何实现图像的压缩。 相似文献
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A new nested visual cryptography scheme is proposed for n cooperated user groups. It can encode the secret image consists of black and white pixels into share images which should be distributed to each user in each group. To decode the secret, users in at least k out of n groups should be present, and at least p out of q users should provide their shares for each attendant group (where p and q can be distinct for each group). For the proposed scheme, the known scheme can be regarded as a simple instance which has only one user in each group. Compared to S-extended visual cryptography scheme, there is no need to enumerate all the user sets which can decode the secret. 相似文献
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YuanZhonglan XiaGuangsheng WenQiaoyan YangYixian 《电子科学学刊(英文版)》2005,22(4):364-370
All watermarks are shared into shadow images using VCS(Visual Cryptography Scheme). Only one specific shadow (as a new watermark) is embedded into the host signal and the other ones are distributed to every user in each group as a key. In the watermarking extraction procedure, users in different group can obtain different watermark by combining their shadows with the extracted one from the watermarked signal. Analysis and experimental results show that the new watermarking method is novel, secure and robust. 相似文献
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On the Contrast in Visual Cryptography Schemes 总被引:16,自引:0,他引:16
A visual cryptography scheme is a method to encode a secret image SI into shadow images called shares such that certain qualified subsets of shares enable the ``visual' recovery of the secret
image. The ``visual' recovery consists of xeroxing the shares onto transparencies, and then stacking them. The shares of
a qualified set will reveal the secret image without any cryptographic computation.
In this paper we analyze the contrast of the reconstructed image in k out of n visual cryptography schemes. (In such a scheme any k shares will reveal the image, but no set of k-1 shares gives any information about the image.) In the case of 2 out of n threshold schemes we give a complete characterization of schemes having optimal contrast and minimum pixel expansion in
terms of certain balanced incomplete block designs. In the case of k out of n threshold schemes with we obtain upper and lower bounds on the optimal contrast.
Received 27 September 1996 and revised 13 February 1998 相似文献
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《电子学报:英文版》2016,(4):621-624
In binary Region increm enting visual cryptography schemes (RIVCSs), the secrets of multi-ple secrecy regions can be gradually revealed by hu-man visual system. A characteristic of the existing binary RIVCSs different from traditional binary Visual cryptog-raphy schemes (VCSs) is that, the contrasts for different revealed regions are different while traditional binary VCSs have same contrast. To keep the quality (contrast) of re-covered image compatible with the traditional VCS, we use integer linear programming to design a binary (k,n)-RIVCS with same contrast for all secrecy regions in this paper. Experimental results demonstrate that our method is feasible and effective. The trade-off is that our schem e involves a larger pixel expansion. 相似文献