共查询到18条相似文献,搜索用时 171 毫秒
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目前提出的许多关于二值可视密码方案的论文都致力于研究在可视秘密共享方案里如何使像素扩展比较小或恢复图像的对比度比较高的问题。基于Shamir的秘密共享方案的思想,提出一种新的二值图像(k,n)-VCS可视密码方案。该方案利用二元域上线性方程组解的特征及多层(k,k)-VCS构造基础矩阵S0,S1,给出一个强的访问结构,从而获得(k,n)-VCS可视密码方案更小的像素扩展。 相似文献
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本文提出了一种基于取反运算可获得理想对比度的可视密码方案,适用于一般存取结构可以实现秘密图像无失真地恢复,并且没有像素扩展。该方案应用了简单的布尔运算实现了传统可视密码方案中单纯的叠加运算无法实现的功能。 相似文献
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可视密码是一种可以通过人眼直接解密的秘密共享方法,可视密码具有隐蔽性强、高安全性、秘密恢复简单性和具有通用性等优点,但是可视密码也一直存在像素扩展和对比度差的弊端。为了解决可视密码像素扩展的问题,王洪君等提出了像素不扩展的(2,3)视觉密码方案,本文在王洪君等人研究基础上,对(2,3)可视密码做了进一步改进,在保证像素不扩展的前提下,恢复秘密图像时可以得到更好的对比度。 相似文献
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利用矩阵并的思想给出了一般存取结构下分存图有意义的可视分存方案(称作扩展可视分存方案),得到像素膨胀值,并且构造了一般存取结构的彩色图像扩展可视分存方案,得到彩色(k,n)扩展方案的最优像素膨胀. 相似文献
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针对防共谋欺骗可视密码存在像素扩展度大的问题,通过对秘密图像的不同像素列,随机选取不同像素扩展度的加密矩阵进行分享,构造出一种防共谋欺骗可视密码方案.理论与实验结果表明,该方案能够实现防共谋欺骗功能,且参与者不需要持有额外的验证共享份,同时优化了像素扩展度,减小了共享份的存储和传输开销. 相似文献
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为解决传统可视密码像素膨胀及分存图像无意义等问题,提出一个基于半色调技术的(2,2)可视密码方案。方案中密图为黑白反色图像,利用半色调技术将一幅灰度图像处理后的半色调图像作为掩盖图像一,然后对其进行反色运算得到掩盖图像二,根据密图修改掩盖图像生成分存图像,叠加分存图像恢复密图。该方案符合可视密码解密简单的特性且分存图像有意义、没有引入任何像素膨胀。 相似文献
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Visual secret sharing (VSS) scheme is an encryption technique that utilizes the human visual system in recovering the secret image and does not require any cryptographic computation. Pixel expansion has been a major issue of VSS schemes. A number of probabilistic VSS schemes with minimum pixel expansion have been proposed for binary secret images. This paper presents a general probabilistic (k, n)-VSS scheme for grey-scale images and another scheme for color images. With our schemes, the pixel expansion can be set to a user-defined value. When this value is 1, there is no pixel expansion at all. The quality of reconstructed secret images, measured by average contrast (or average relative difference), is equivalent to the contrast of existing deterministic VSS schemes. Previous probabilistic VSS schemes for black-and-white images can be viewed as special cases in the schemes proposed here. 相似文献
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Daoshun Wang Author Vitae Lei Zhang Author Vitae Author Vitae Xiaobo Li Author Vitae 《Pattern recognition》2007,40(10):2776-2785
Traditional secret sharing schemes involve complex computation. A visual secret sharing (VSS) scheme decodes the secret without computation, but each shadow is m times as big as the original. Probabilistic VSS solved the computation complexity and space complexity problems at once. In this paper we propose a probabilistic (2,n) scheme for binary images and a deterministic (n,n) scheme for grayscale images. Both use simple Boolean operations and both have no pixel expansion. The (2,n) scheme provides a better contrast and significantly smaller recognized areas than other methods. The (n,n) scheme gives an exact reconstruction. 相似文献
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针对目前可视密码术引起的像素膨张、与原密图相比,叠合图像的亮度、对比度降低问题,提出一种新的基于分块字典的可视密码改进方法。该方法首先根据确定大小的像素分块,列举每个子图各子块像素分布情况后建立相应的分块字典,并对分块字典条目进行编号;然后对原密图置乱后,将原密图分成两个子密图;再分别两个子密图进行均匀分割,将其分成若干子块,所有密图子块对应一个字典编号并进行一维化,则得出由两个子图所有子块编号组成的序列。由此,密图就由这个分块字典编号序列所确定,经过传输后,提取并组成字典编号序列,二维还原后与相应的分块字典条目对应,装配得出两个子图叠合后还原成原密图。与以前的可视密码算法,如(k,n)门限方案等相比,采用子图交错叠合、基于分块字典的可视密码改进方法,可减少算法复杂度,编码的比特序列长度是对原密图直接编码后的比特序列长度的两倍,从而减少像素膨胀,也不会引起叠合图像的亮度、对比度降低的问题。从而更具实用性。 相似文献
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Traditional secret sharing scheme that encrypts secret image based on mathematical calculation to construct shadows often requires the complicated computation to extract the secret. Later on, conventional visual cryptography scheme was developed to deal with the perplexed calculation in encryption and extraction of previous schemes. The stack-to-see technique can be used easily to reveal the secret by human visual system, which can shorten computation time. However, the expansion of image size and the noise-liked shares of previous schemes lead to the difficulty in transmission and storage. This study uses a pre-defined codebook to encode two secret images into two meaningful transparencies without pixel expansion. According to the turning mechanism, two secret images can be embedded into two shares simultaneously. The decryption process allows the user to get two secrets via turning and stacking. A notable feature of our scheme is that the black pixel value of the secret image can be completely extracted and the vision quality of stacking results can be identified clearly. 相似文献
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The optimal pixel expansion is an important parameter of deterministic visual cryptography scheme (DVCS). There are many researches have been done under different access structures and stacking operations. However, any necessary or sufficient condition has not been found about the optimal pixel expansion. In this paper, we give a necessary condition of the optimal pixel expansion of DVCS for the first time, which is suitable for any access structure and any stacking operation. Furthermore, a pixel expansion optimization algorithm has been designed to improve the existing schemes. It is found that the pixel expansion can be reduced for most DVCS based on XOR operation. Finally, we give some experimental results and comparisons to show the effectiveness of the proposed scheme. 相似文献
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Tzung-Her ChenAuthor Vitae Kai-Hsiang TsaoAuthor Vitae 《Journal of Systems and Software》2011,84(7):1197-1208
A new visual secret sharing (VSS) approach by random grids (RG-based VSS), proposed by Kafri and Keren (1987), has drawn close attention recently. With almost all advantages of visual cryptography-based VSS, RG-based VSS benefits more from keeping the same size of secret images without the problem of pixel expansion from which VC-based VSS suffer. In this paper, a threshold RG-based VSS scheme aiming at providing the wide-use version is presented. This is the first effort to develop the technique. The experimental results and theoretically analysis in visual quality and security show that the proposed scheme performs well. 相似文献
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In traditional VSS schemes, the size of the share image is substantially expanded since each pixel of the secret image is mapped onto a block consisting of several pixels. In addition, the quality of the reconstructed secret image is normally degraded in contrast, especially for halftone images. This study proposes a VSS scheme that maps a block in a secret image onto one corresponding equal-sized block in each share image without image size expansion. Two types of techniques, including histogram width-equalization and histogram depth-equalization, are proposed to generate the corresponding share blocks containing multiple levels rather than two levels based on the density of black pixels on the blocks for a secret block. In the former technique, the gray-scale image histogram is obtained by uniformly splitting the range of the pixel gray levels in the secret image, while in the latter the buckets are created so that the area of each bucket is roughly constant by containing approximately the same number of pixels. The proposed schemes significantly improve the quality of the reconstructed secret image compared to several previous investigations. 相似文献