摘要
像素不扩展视觉密码方案在秘密图像分享过程中伴随有秘密信息损失,存在秘密图像细节内容恢复不佳、恢复图像质量不高的问题.本文提出了一种基于两级阈值的像素不扩展视觉密码方案,从图像空域角度出发,依据像素块黑色像素分布密度,采取块尺寸由大到小调整、分类处理的方法,以一级阈值区分秘密图像中低频和高频区域,进而采取不同的分享方法,低频区域作为纯色像素块分享,以二级阈值调控高频区域中单位块灰度与分享矩阵的映射关系,达到增强恢复图像中部分细节表现的效果.该方案提升了恢复图像整体视觉效果,增强了细节内容处理能力.理论证明本方案具有与确定型视觉密码相同的安全强度,实验结果和对比分析验证了本方案的有效性.
The reconstructed image of the size-invariant visual cryptography(VC)is inevitably accompanied by the loss of secret image information,which leads to poor visual quality of detailed information in the reconstructed image.In this paper,we propose a two-level threshold based multi-pixel encryption VC scheme,in which block classification is adopted according to the blackness from the spatial view of point and the size of each shared secret pixel block is adaptively adjusted.The first level threshold is utilized to distinguish pure color blocks.The second level threshold is utilized to control the selection of sharing matrix for basic block so as to emphasize the specific details.In doing so,the proposed scheme improves the capability for processing detailed information and the visual quality of the reconstructed image.The proposed scheme is as secure as the traditional VC scheme and experimental results demonstrate the effectiveness of the proposed scheme.
作者
孙瑞
付正欣
李小鹏
郁滨
SUN Rui;FU Zheng-Xin;LI Xiao-Peng;YU Bin(Information Engineering University,Zhengzhou 450001,China)
出处
《密码学报》
CSCD
2021年第4期572-581,共10页
Journal of Cryptologic Research
基金
国家自然科学基金项目(61602513)。
关键词
视觉密码
视觉秘密分享
多像素加密
像素不扩展
视觉质量
visual cryptography
visual secret sharing
multi-pixel encryption
size invariant
visual quality
