BVCS: SHARING VISUAL SECRETS IN SINGLE IMAGE RANDOM DOT STEREOGRAMS

Visual cryptography (VC) is a technique that encrypts a secret image into n shares, with each participant holding one  share;  Conventional   VCSs   suffer   from   a   transmission   risk problem  because  the  noise-like  shares  will  raise  the  suspicion of  attackers  and  the  attackers  might  intercept the  transmission. Previous   research   has   involved   in   hiding   shared   content   in halftone shares to reduce these risks, but this method exacerbates the  pixel   expansion   problem  and   visual   quality  degradation problem  for  recovered  images. In  this  abstract,  a  binocular  VCS (BVCS), called the ( 2 , n ) -BVCS, and an encryption algorithm are proposed  to  hide  the  shared  pixels  in  the  single  image  random dot  stereograms  (SIRDSs).  Because  the  SIRDSs  have  the  same 2D  appearance  as  the  conventional  shares  of  a  VCS,  this  paper tries  to  use  SIRDSs  as  cover  images  of  the  shares  of  VCSs to  reduce  the  transmission  risk  of  the  shares.  The  encryption algorithm  alters  the  random  dots  in  the  SIRDSs  according  to the  construction  rule  of  the ( 2 , n ) -BVCS  to  produce  nonpixel- expansion shares of the BVCS. Altering the dots in a SIRDS will degrade the visual quality of the reconstructed 3D objects. Hence, we  propose  an  optimization  model  that  is  based  on  the  visual quality requirement of SIRDSs to develop construction rules for a ( 2 , n ) -BVCS that maximize the contrast of the recovered image in the BVCS.