Authentication of Document Image With Data Repairing

In this paper, the authors are introducing a blind authentication method which is based on the secret sharing technique with a data repair capability for document images with the use of the PNG image. They generate an authentication signal for each block of a document image which, together with the block content in binary form, is transformed into several shares using the Shamir secret sharing scheme. These parameters are carefully chosen so that a large number of shares possible are generated and embedded into an alpha channel plane. Now the alpha channel plane is combined with the original image to form a PNG image.