CAJ | 학술논문

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.
침대목전가시밀마술인기적상소팽장、여원밀도상비,첩합도상적량도、대비도강저문제,제출일충신적기우분괴자전적가시밀마개진방법.해방법수선근거학정대소적상소분괴,열거매개자도각자괴상소분포정황후건립상응적분괴자전,병대분괴자전조목진행편호;연후대원밀도치란후,장원밀도분성량개자밀도;재분별량개자밀도진행균균분할,장기분성약간자괴,소유밀도자괴대응일개자전편호병진행일유화,칙득출유량개자도소유자괴편호조성적서렬.유차,밀도취유저개분괴자전편호서렬소학정,경과전수후,제취병조성자전편호서렬,이유환원후여상응적분괴자전조목대응,장배득출량개자도첩합후환원성원밀도.여이전적가시밀마산법,여(k,n)문한방안등상비,채용자도교착첩합、기우분괴자전적가시밀마개진방법,가감소산법복잡도,편마적비특서렬장도시대원밀도직접편마후적비특서렬장도적량배,종이감소상소팽창,야불회인기첩합도상적량도、대비도강저적문제.종이경구실용성.
In order to avoid pixel expansion and contrast of the gathered secret image compromise,a new visual cryptographic scheme,which is called visual cryptographic scheme with sub-block coding method,is presented.Instead of taking m subpixels to represent one pixel,the share image is divided into sub-blocks with same size,each of which is taken as a unit to encode and with same pixel size.Then sub-block coding method is adopted to convert each shadow image to numbers matrix,that is,every sub-block meets a number.After that,according to a secret key,these two number matrices are converted into a series of number.Last the series is encrypted to transport or do some other operations.This scheme is compared to the (k,n) visual secret sharing scheme in section 4 and it shows that there do not exist pixel expansion and contrast compromise in this new scheme.