Improving capacity of Hamming (n,k)+1 stego-code by using optimized Hamming + k

The Hamming coding (n,k)+1 data hiding (H1DH) scheme is based on matrix encoding and has the characteristic of a good embedding efficiency. This scheme improves the embedding efficiency of Hamming coding (n,k) data hiding (HDH). H1DH is used to hide a k+1 bit in a (n+1) block by adding or subtracting one. However, the embedding rates of HDH, H1DH, and HCIH are only 0.43, 0.5, and 0.75 respectively. The important criterion of data hiding is the amount of embedding capacity with a high PSNR in a cover image. In this paper, we propose a Hamming coding (n,k)+k data hiding (HkDH) scheme to hide 2k bits in a block with overlapped LSB and 2LSB using matrix encoding by adding or subtracting by two. In order to hide 2k bits in a block, it is necessary to increase or decrease by one, two or three. Assuming that we need two modifications to hide 2k bits in a block and the location of two modifications is the same, the collision problem occurs in the block. We suggest an optimal method for hiding 2k bits in a block and verify the proposed method. The main contribution of this paper is theoretically proving that our HkDH scheme has a better embedding capacity than HDH, H1DH, EMD, and HCIH while not seriously degrading the PSNR.