Abstract
This article proposes an image tamper detection and correction technique. It uses the principle of differencing and addresses the fall off boundary problem (FOBP). It operates on 2 × 2 non-overlapped blocks. From each pixel of a block the decimal value for 4 most significant bits (MSBs), is called as quotient, and the decimal value for 4 least significant bits (LSBs) is called as remainder. The 4 watermark bits (WBs) are computed from 4 quotients as the root of Merkle tree. These 4 WBs are XORed with the 4 bits generated from logistic map sequence to generate the 4 recovery bits (RBs). The 4 WBs and 4 RBs are stored in 4 remainders by LSB alteration and remainder value differencing (RVD). While extracting the watermark, the tampered blocks can be identified and a correction logic can be applied to get the true value of the pixels in the block. The peak signal-to-noise ratio (PSNR) value is 42.02 dB and structural similarity (SSIM) index value is 0.9765. The tampered blocks can be accurately identified and corrected.
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