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The Scientific World Journal
Volume 2014 (2014), Article ID 895063, 12 pages
http://dx.doi.org/10.1155/2014/895063
Research Article

A New Pixels Flipping Method for Huge Watermarking Capacity of the Invoice Font Image

1Institute of Graphics and Image, Hangzhou Dianzi University, Hangzhou, Zhejiang 310018, China
2Institute of Digital Media, Hangzhou Dianzi University, Hangzhou, Zhejiang 310018, China
3University of Yamanashi, Yamanashi-ken 409-3866, Japan
4Department of Information Engineering and Computer Science, Feng Chia University, Taichung 40724, Taiwan
5Department of Computer Science and Information Engineering, Asia University, Taichung 41354, Taiwan

Received 22 July 2014; Accepted 2 September 2014; Published 12 November 2014

Academic Editor: Fei Yu

Copyright © 2014 Li Li 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.

Abstract

Invoice printing just has two-color printing, so invoice font image can be seen as binary image. To embed watermarks into invoice image, the pixels need to be flipped. The more huge the watermark is, the more the pixels need to be flipped. We proposed a new pixels flipping method in invoice image for huge watermarking capacity. The pixels flipping method includes one novel interpolation method for binary image, one flippable pixels evaluation mechanism, and one denoising method based on gravity center and chaos degree. The proposed interpolation method ensures that the invoice image keeps features well after scaling. The flippable pixels evaluation mechanism ensures that the pixels keep better connectivity and smoothness and the pattern has highest structural similarity after flipping. The proposed denoising method makes invoice font image smoother and fiter for human vision. Experiments show that the proposed flipping method not only keeps the invoice font structure well but also improves watermarking capacity.