An adaptive tri-pixel unit steganographic algorithm using the least two significant bits

Steganography has various useful applications. In this paper, a steganographic algorithm with high payload and low change rate is proposed. Three pixels are processed as a unit, the exclusive-or result of the second least significant bits (SLSBs) of the pixels in that unit is regarded as the flag. According to the value of the flag, as well as the Hamming distance between the least significant bits (LSBs) and the secret messages, three bits of secret message are embedded. Secret message can be easily extracted depending on the value of flag. Local texture is also considered to achieve adaptive embedding. The advantage of the proposed algorithm is that at most one pixel will be modified when embedding three bits of message into three pixels. Simulation results showed that the proposed algorithm decreases the probability of detection for steganalysis methods and the security has been much improved.