QUANTIZATION-BASED FRAGILE WATERMARKING USING BLOCK-WISE AUTHENTICATION AND PIXEL-WISE RECOVERY SCHEME FOR TAMPERED IMAGE

This paper suggests an efficient fragile watermarking scheme for image content authentication along with altered region restoration capability. In this scheme, image is divided into nonoverlapping blocks of size 2 x 2 and for each block, eight bits for image content recovery data and four bits for authentication data from five most significant bits (MSBs) of each pixel, are generated. These 12 bits are embedded into the least significant bits (LSBs) of the pixels which are placed in its corresponding mapping block. At the receiver end by comparing the recalculated and extracted authentication data, the tampered blocks can easily be identified and using recovery data, one can easily restore the tampered block. Results of experiments demonstrate that the proposed scheme is effective enough for alteration detection as well as tamper recovery of the image.