A data hiding technique by mixing MFPVD and LSB substitution in a pixel
Keywords:Steganography, PVD, MF PVD, PDH analysis, RS analysis, data hiding
AbstractPixel difference range mismatch at sender and receiver is a main problem with pixel value differencing (PVD) steganography techniques. This paper proposes a mixed technique combining PVD and LSB to address the above problems. The PVD uses modulus function (MF) and multi-directional edges. It uses 2×3 size pixel blocks to exploit the edges in five directions. The first two LSBs of every pixel forms the lower bit plane (also called as remainder plane) and the remaining six MSBs form the higher bit plane (also called as quotient plane). LSB substitution is applied at remainder plane and PVD is applied at quotient plane. From the 2×3 size pixel block, a 2×3 quotient block is formulated. A quotient is obtained after dividing the pixel values by 4. Thus from the pixel block a quotient block is obtained. The central quotient in the quotient block is considered as reference value and five difference values with five neighboring quotients are calculated. Based on the average of these five difference values, the hiding capacity in all the five directions is decided. The remainder plane of central pixel acts like indicator, so that extraction can be done successfully from the five neighboring pixels at the time of extraction. The experimental results show the evidence that the proposed technique does not show the step effects, so will not be vulnerable to PDH analysis. Furthermore, it is also observed that the recorded hiding capacity value is larger than the existing techniques without decreasing the PSNR.
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