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Since digital media is gaining popularity nowadays, people are more concerned about its integrity protection and authentication since tampered media may result in unexpected problems. Considering a better media protection technique, this paper proposes an efficient tamper detection scheme for absolute moment block truncation coding (AMBTC) compressed images. In AMBTC, each image block is represented by two quantization levels (QLs) and a bitmap. Requiring insignificant computation cost, it attracts not only a wide range of application developers, but also a variety of studies to investigate the authentication of its codes. While the existing methods protect the AMBTC codes to a large extent, the leakage of some unprotected codes may be insensitive to intentional tampering. The proposed method fully protects the AMBTC codes by embedding authentication codes (ACs) into QLs. Meanwhile, the most significant bits of QLs are symmetrically perturbed to generate the candidates of ACs. The ACs that cause the minimum distortion are embedded into the least significant bits of QLs to minimize the distortion. When compared with prior works, the experimental results reveal that the proposed method offers a significant sensitivity-of-tamper property while providing a comparable image quality.

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In this paper, we proposed an improved data hiding scheme to embed secret data in the compressed bitstreams where the quality of the image is maintained even after embedment. The difference in the quantized values for each block is used to determine whether only 1 bit of secret is to be hidden for the block or to toggle bits in the bitmap to hide more bits. The scheme has a high payload and is a no distortion data hiding. Experimental tests with Lena showed that in the 2x2 block-sized BTC compressed bitstreams, an additional 10 488 bits were embedded and 416 bits for the 46x4 block-sized. The new improved scheme increases payload and is reversible