Affiliations: Department of Computer Science and Engineering,
National Chung Hsing University, Taichung 402, Taiwan, ROC.
phd9214@cs.nchu.edu.tw | Department of Information Engineering and Computer
Science, Feng Chia University, Taichung 407, Taiwan, ROC. ccc@cs.ccu.edu.tw | Department of Computer Science and Engineering,
National Chung Hsing University, Taichung 402, Taiwan, ROC.
jkjan@cs.nchu.edu.tw
Note: [] Address for correspondence: Department of Information
Engineering and Computer Science, Feng Chia University, Taichung 407, Taiwan,
ROC
Abstract: In this paper, watermarking authentication schemes for binary images
are investigated. Dual-Pair Blocks (DPBs), 2 × 2 blocks with two
black and two white pixels, are employed as the basic units of information
embedding. With 6 distinctive patterns obtained by pixel patterns, a DPB can be
represented by a senary value as the embedding information. Variable length
coding is adopted to enhance the information embedding capacity of the DPB. The
secret key of the watermarking is a pseudo random function with a seed value,
which selects DPBs for information embedding. Based on the aforementioned
framework, two novel watermarking schemes are presented. The first one, named
dual-pair block authentication (DPBA), is an irreversible one featuring high
information embedding capacity, and well visual quality. The second scheme,
named senary Huffman compression authentication (SHCA) scheme, supports
reversible watermarking unique in the literature. Matching-pair technique is
further employed both schemes to reduce the number of altered bits after
watermarking for better visual quality. Experimental results show that, the
DPBA scheme has the highest information embedding capacity on all comparing
schemes. The average compression ratio of the reversible SHCA scheme is up to
38.96%. The average distortion rates per accessed DPB for the proposed DPBA and
SHCA schemes are 0.485 and 0.46, respectively.
