Image Steganography Based on Sub-Band Coefficient Adjustment in BDCT Domain

This study presented a new steganography method for hiding information in an image. For improving the transparency and robustness of information hiding, a visual model was employed to calculate the block based just noticeable difference (JND), and the three sub-bands of coefficient matrix of block discrete cosine transform (BDCT) were defined for embedding objects. Firstly, an information file was transferred into a binary watermark sequence, which was encoded by redundant encoding method and scrambled randomly. Then, two neighboring image blocks are selected each time from the carrier image by Hilbert scanning order, and transformed by BDCT. And then according to the JND and the watermark bit, the BDCT sub-band coefficients at same position of two neighboring blocks were adjusted to hide the information. Lastly, the inverse BDCT was executed to get the stego-image. The experiments show that the hidden information is invisible, and the algorithm is robust to general image processing operations.