Research on aspect ratio invariant visual threshold schemes
Fang Li-guo · Jisuanji gongcheng yu sheji · 2006
If the pixel expansion m is not a square value,the secret image-a foursquare will be changed to a rectangle and consequentlylead to the loss of information after performing the VCS technique.The relationship between two improved schemes,which solved theproblem of aspect ratio variant is proved.At the same time a scheme of encrypting after increasing the secret image is provided toencrypt the edge of the image.Simulation results demonstrate that this scheme is effective.