A novel LSB data hiding scheme with the lowest distortion

The proposed scheme groups three pixels as an embedding unit to conceal three bits of secret data in which the possible modification for each pixel is at most +1 or -1. With our new scheme, the probability of altering one pixel by adding 1 or subtracting 1 is 6/8; it is 1/8 when altering two pixels, and 1/8 when preserving pixels without any modification. In conventional algorithms, the expected number of modification per pixel (ENMPP) mostly ranges from 0.375 to 0.5 on average when the embedding capacity of each pixel is one bit of secret message. In contrast, our new scheme groups three pixels together to convey three bits of secret message. The ENMPP is reduced at least by 0.333 on average. As a result, our algorithm offers higher visual quality for the stego image. The experimented results have verified that our scheme is super to the previous algorithms.