Data hiding based on extended turtle shell matrix construction method

Data hiding research has focused mainly on determining how to embed secret data into various public host media, and to also ensure the host medium is not changed to a degree such that it can be perceived by the human eye. In 2014, Chang et al. proposed a novel concept, named the turtle shell matrix, to embed secret data. This scheme has obvious advantages with respect to its hiding capacity and image quality. However, its disadvantage is lack of flexibility due to the fixed turtle shell matrix structure. In this paper, we extend this turtle shell matrix structure into a different matrix model to meet different hiding capacity and image quality needs. Meanwhile, a general extraction function is derived to generate a matrix having a different turtle shell model. The values of the pixel pairs in the cover image are modified according to guidance provided by the turtle shell to hide a secret digit in an N-ary notational system. The experimental results show that the proposed scheme not only has better flexibility in balancing the trade-off between hiding capacity and stego-image quality, but also provides higher hiding capacity and stego-images with better visual quality than previous schemes.