An AMBTC Authentication Scheme With Recoverability Using Matrix Encoding and Side Match

This paper presents an authentication scheme with recoverability based on Absolute moment block truncation coding (AMBTC). Previous works do not take into account characteristics of the AMBTC compressed codes. Therefore, the qualities of marked and recovered images are not satisfactory. In this paper, we generate the recovery codes according to block similarities. The recovery codes are scrambled and stored in the bitmaps of smooth blocks using Matrix encoding. The bits in the bitmap are flipped to obtain a set of authentication codes. The code that causes the least error is embedded into the quantization values using the adaptive pixel pair matching technique (APPM). For those complex blocks, the authentication codes are generated from the bitmaps, and are embedded into the quantization values. After authenticating, the tampered blocks are recovered by untampered ones with the same cluster information. Some blocks that cannot be recovered in the previous stage are recovered by using the Side match technique. The experimental results show that our method provides better image quality and recoverability than prior works.