An Intragroup and Intergroup Multiple Secret Images’ Sharing Scheme with Each Participant Holding One Shadow Image
Algorithm 2
The recovery process of the SIS within one group and between groups.
Input: the shadow images , the order numbers of the participants and the order numbers of the authorized shared participants.
Output: the recovered images
Step 1: determine the shadow images participating in the recovery of , respectively.
Step 2: repeat Steps 3 and 4 for each pixel of the corresponding shadow images in each group. are used to recover ; intergroup shadow images are used to recover , where .
Step 3: calculate in the field of by the Lagrange interpolation formula .
Step 4: set to calculate the recovered secret pixel value in each group.
