An improved module-based substitution method for image hiding

The paper proposes an improved module-based substitution method for image hiding. The method has the following characteristics: (1) The extracted data are lossless. (2) Each k-bit datum is hidden in a pixel of the host image, and the gray-value distortion is not larger than 2^k-1 for most of the pixels. (3) If it is compared with reported lossless Least-Significant-Bits (LSB) or module-based methods, the proposed method is often with better stego-image quality, unless the hidden data are with very strong randomness. (4) The time complexity is also competitive.