A Steganographic Method Combining LSB Substitution and PVD in a Block

In the recent past some steganography techniques by combining least significant bit (LSB) substitution and pixel value differencing (PVD) have been proposed to improve upon the hiding capacity and peak signal-to-noise ratio (PSNR). This paper proposes a steganographic technique by using both LSB substitution and PVD with in a block. The image is partitioned into 2×2 pixel blocks in a non-overlapping fashion. For every 2×2 pixel block the upper-left pixel is embedded with k-bits of data using LSB substitution. Then the new value of this pixel is used to calculate three pixel value differences with the upper-right, bottom-left, and bottom-right pixels of the block. Then data bits are hidden using these three difference values in three directions. Both horizontal and vertical edges are considered. There are two variants proposed by using two different range tables. In the first variant (Type 1) the PSNR is improved and in the second variant (Type 2) both PSNR and hiding capacity are improved.