ROI Based Steganography Method Using Two Bit LSB Replacement and Entropy Calculation

Abstract

Different challenges in steganography are Imperceptibility, Robustness and Capacity. In this paper, all these points have been considered and a secure steganography method has been proposed to hide secret information. Self-embedding method has been adopted in which secret information has been taken from the Region of interest selected by a cropping tool. As MSB bits contain most of the information, only MSB bits has been embedded and rest of the LSB bits from the same chosen place can be used for embedding mechanism. Also two bit LSB replacement has been used for embedding data which is decided based on entropy information from a set of non-overlapping blocks of the input image. Maximum entropy has been chosen to select that block first which has maximum value among all. Entropy has been calculated only for MSB bits which results in same sorting sequence of blocks at the receiver side as well hence results in extraction of secret information in the same manner as embedding. XOR embedding has been implemented before embedding in order to secure the data. Proposed method has dual embedding capacity as two bit replacement has been used as compared to the existed method.