دانلود A steganographic method combining LSB substitution and PVD in a block

Abstract

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.