A Novel Data Hiding Scheme for Binary Images with Low Distortion

In this paper, we propose a novel data hiding scheme for binary image which is capable of significantly reducing the visual artifacts caused by secret data embedding. Our new scheme includes three parts. Firstly, the cover image represented by a binary sequence of 0 or 1 pixel values is subdivided into blocks of sub-images. For each block we introduce a simple yet efficient scheme to estimate a pixel's "flippable value" by examining its neighbor. We give high "flippable value" to a pixel where its neighbors are much different from the current pixel value being examined. Secondly, we utilize the Arnold transform to shuffle the binary image into a noise image. The transformation is conducted several times until each block of sub-image contains at least one pair of pixels with "flippable value," which indicates that this block of sub-image is feasible to embed a bit of secret message by flipping the corresponding pixel value. Finally, we present a novel data embedding technique, which employs three blocks of sub-image as a basic embedding unit. This technique ensures the basic unit to convey 3 bits of secret message by at most flipping two pixels with "flippable values" on any of two blocks. Our scheme belongs to the blind extraction where the secret data can be extracted without referring to the cover image. Experimental results show the stego image produced by our scheme is imperceptible to the human eyes. Comparing to existing schemes, our method produces the least image distortion, being 0.333 bits per pixel.