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Mathematical Problems in Engineering
Volume 2017 (2017), Article ID 3509258, 10 pages
Research Article

An Efficient Image Watermarking Method Based on Fast Discrete Cosine Transform Algorithm

1Department of Computer Science and Information Engineering, Chang Jung Christian University, Tainan City 701, Taiwan
2Asian Institute of Telesurgery, Changhua County 500, Taiwan
3Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan City 701, Taiwan

Correspondence should be addressed to S. E. Tsai

Received 15 February 2017; Revised 24 May 2017; Accepted 21 June 2017; Published 16 August 2017

Academic Editor: Raffaele Solimene

Copyright © 2017 S. E. Tsai et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This paper proposes an image watermarking method based on the fast discrete cosine transform (DCT) algorithm for implementation in digital signal processor. A digital watermark can be effectively embedded and efficiently extracted without the host image. The keys in watermarking process include four frequency coefficients in DCT, two random permutation vectors, and a quantization matrix for normalizing the watermark and the host image. The fast DCT algorithm has been shown to reduce the complexity of two-dimensional image transformation so that embedding/decoding an image watermark can be completed in real time within 0.33 seconds. The quality of both watermarked image and extracted (retrieved) watermark remains excellent. It is shown that the watermarking method is efficient in and robust to data cropping, transmission loss, and compression/decompression.