An Authentication Method for AMBTC Compressed Images Using Dual Embedding Strategies

Abstract

In this paper, we proposed an efficient authentication method with dual embedment strategies for absolute moment block truncation coding (AMBTC) compressed images. Prior authentication works did not take the smoothness of blocks into account and only used single embedding strategies for embedment, thereby limiting image quality. In the proposed method, blocks were classified as either smooth or complex ones, and dual embedding strategies used for embedment. Respectively, bitmaps and quantized values were embedded with authentication codes, while recognizing that embedment in bitmaps of complex blocks resulted in higher distortion than in smooth blocks. Therefore, authentication codes were embedded into bitmaps of smooth blocks and quantized values of complex blocks. In addition, our method exploited to-be-protected contents to generate authentication codes, thereby providing satisfactory detection results. Experimental results showed that some special tampering, undetected by prior works, were detected by the proposed method and the averaged image quality was significantly improved by at least 1.39 dB.