Affiliations: Department of Computer Science, National Pingtung
University of Education, Pingtung, Taiwan 900, ROC. chyang@mail.npue.edu.tw | Department of Computer Science, National Tsing-Hua
University, Hsinchu, Taiwan 300, ROC. cyweng@is.cs.nthu.edu.tw | Department of Information Management, Central Police
University, Taoyuan, Taiwan 333, ROC. sjwang@mail.cpu.edu.tw | Department of Computer Science, National Tsing-Hua
University, Hsinchu, Taiwan 300, ROC. hmsun@cs.nthu.edu.tw
Note: [] Address for correspondence: Shiuh-JengWang, Dept. of
InformationManagement, Central Police University, Taoyuan, Taiwan 333, ROC
Abstract: Digital watermarking techniques are an importantmethod to provide
copyright protection of multimedia. In this paper, we proposed a non-embedded
watermarking scheme, based on vector quantization (VQ), to protect the image
copyright. Our approach applies a codebook to generate a relationship between
image blocks and watermark bits, and then the relationship is outputted as the
key stream (called KS). With the KS, the relationship between the image and the
watermark are confirmed and the copyright of the image is declared. In our
method, the number of bits that are related to a block is adaptive. Compared to
the scheme of Lin et al., our approach needs only one codebook, while their
approach requires seven. Moreover, in our approach each block can be connected
with watermark bits, while some blocks can not be connected with watermark bits
in their method. Finally, a method of adjusting the robustness is given for our
proposed approach. Our approach not only reduces the length of the key stream,
but it also allows for a more flexible application. In addition, our
experimental results show that the proposed approach runs faster and is more
robust than that of Lin et al.
