Watermarked Data Hiding for Binary Images by Two Stage Referencing

This paper proposes a new data hiding method for two-color images by two stage referencing. The cover image is partitioned into n x n non-overlapping sub-blocks, and calculated different values by two stages for all pixel to find the suitable replacement pixel. For a one stage, neighboring pixels with (n+2) times (n+2) are used to obtain difference value which is different with the current pixel value and (n+4) times (n+4) pixels are referenced for next stage. These two values are used to embed a secret bit on a sub-block. The experimental results show that the proposed method achieves a good visual quality for the watermarked image and a high capacity for various n x n sub-block.