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Halftone Visual Cryptography (HVC) is an encryption technique that encodes the secret image into halftone images in order to produce secure meaningful shares. Many methods have been proposed for developing HVC to protect the security of the images. Yet, these methods still have some problems such as poor visual quality of shares, large pixel expansion, interference of secret image on shared images, and interference shared images on retrieved image. To solve such problems, an optimized HVC scheme (OHVCS) using Error Diffusion (ED) is proposed in this paper. The proposed scheme eliminates the explicit requirement of codebook and reduces the random patterns of the shared images, as it encodes only the black pixels of the secret image, taking into account that the pixel expansion is the smallest size to be used. Moreover, it performs the basic concept of Visual Cryptography (VC); therefore, the security of the construction scheme is assured. The experimental results, performance evaluation through statistical analysis, and comparison with some existing schemes in various aspects of HVC show the effectiveness of the proposed scheme. 相似文献
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Probabilistic Visual Cryptography Schemes 总被引:1,自引:0,他引:1
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Visual cryptography is an encryption technique that hides a secret image by distributing it between some shared images made up of seemingly random black‐and‐white pixels. Extended visual cryptography (EVC) goes further in that the shared images instead represent meaningful binary pictures. The original approach to EVC suffered from low contrast, so later papers considered how to improve the visual quality of the results by enhancing contrast of the shared images. This work further improves the appearance of the shared images by preserving edge structures within them using a framework of dithering followed by a detail recovery operation. We are also careful to suppress noise in smooth areas. 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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视觉加密是新的加密研究领域,其优点是利用人眼视觉系统的特性直接对被加密的内容进行解码,而不需要用专用软件或硬件进行复杂的解密计算。近年来,由于自动立体显示技术和立体眼镜技术的发展,使得3维显示的应用日趋广泛,而传统的视觉加密方法在3维视频领域内尚无法取得令人满意的效果,因此3维立体视觉加密研究具有重要意义。为了更有效地对3维视频进行加密,利用3维显示的原理和特点,将其与视觉加密的优点相结合,提出了一种3维立体视觉加密新方法,该方法利用人眼视觉特性中的视差特性将隐藏信息巧妙地隐藏在右视图中,实验结果表明,该方法是有效的。 相似文献
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Visual Cryptography for General Access Structures 总被引:4,自引:0,他引:4
Giuseppe Ateniese Carlo Blundo Alfredo De Santis Douglas R. Stinson 《Information and Computation》1996,129(2):86
A visual cryptography scheme for a set ofnparticipants is a method of encoding a secret imageSIintonshadow images called shares, where each participant in receives one share. Certain qualified subsets of participants can “visually” recover the secret image, but other, forbidden, sets of participants have no information (in an information-theoretic sense) onSI. A “visual” recovery for a setX⊆ consists of xeroxing the shares given to the participants inXonto transparencies, and then stacking them. The participants in a qualified setXwill be able to see the secret image without any knowledge of cryptography and without performing any cryptographic computation. In this paper we propose two techniques for constructing visual cryptography schemes for general access structures. We analyze the structure of visual cryptography schemes and we prove bounds on the size of the shares distributed to the participants in the scheme. We provide a novel technique for realizingkout ofnthreshold visual cryptography schemes. Our construction forkout ofnvisual cryptography schemes is better with respect to pixel expansion than the one proposed by M. Naor and A. Shamir (Visual cryptography,in“Advances in Cryptology—Eurocrypt '94” CA. De Santis, Ed.), Lecture Notes in Computer Science, Vol. 950, pp. 1–12, Springer-Verlag, Berlin, 1995) and for the case of 2 out ofnis the best possible. Finally, we consider graph-based access structures, i.e., access structures in which any qualified set of participants contains at least an edge of a given graph whose vertices represent the participants of the scheme. 相似文献
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传统零水印算法构造的水印通常是没有实际意义的二值序列,致使版权辨别不够直观快捷。借鉴视觉密码原理,结合平衡多小波、奇异值分解等技术,提出平衡多小波视觉密码零水印算法。将客户水印作为零水印嵌入到版权图像中,对版权图像进行平衡多小波变换得到实际载体;根据实际载体图像进行块奇异值分解并计算平衡因子得到差值矩阵,由差值矩阵生成过渡矩阵;将过渡矩阵结合2×2视觉秘密图份算法生成图像特征信息;结合图像特征信息和客户水印信息产生零水印。实验结果表明,该算法具有良好的安全性和鲁棒性,是一种可靠的图像版权认证零水印算法。 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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武莉 《计算机光盘软件与应用》2012,(2):80+85
着重地研究了二值图像视觉密码和基本型门限视觉密码。定义了基础矩阵的成组构造特征向量,依据简化的Naor-Shamir模型导出了成组构造特征向量应该满足的方程,进一步求得成组构造特征向量的通解表达式。 相似文献