文档介绍：半调图像数字水印算法研究
专 业z 计算机应用技术硕士生:鱼涛指导教师:孔月萍教授
摘要
当前,纸质图文产品广泛存在于社会生活的各个角落,在极大促进信息共享与交流的同时,常遭遇盗版问题的困扰,产品作者和出版商的利益因此受到损害. 半调图像水印作为一种新的印刷图文产品版权保护技术,可以有效地应对这一问题。
半调是一种将连续色调图像变换为等观感二值图像的技术,半调图像主要是为打印或印刷而生成,在半调图像中隐藏水印信息,可以跳过打印机的半调处理, 有效抵抗对图文印刷产生的攻击。
本文在分析半调图像边缘、纹理和平滑区特性,充分考虑人眼视觉系统掩蔽特性的基础上,提出了基于边缘和模型的半调图像水印算法和一种半调图像分块水印算法。前者结合基于模型的半调技术,在连续色调图像半调处理的同时隐藏水印信息:后者将载体图像分块,按照子块特性采用不同的水印嵌入策略。仿真实验证明,在嵌入适量水印的情况下,这两种方法均能取得较好的水印不可感知性,能够抵抗裁剪、随机涂改、污损等各种常见攻击。
关键词:半调数字水印:打印模型:视觉模型:人眼视觉系统论文类型:应用基础
A Study of Watermarking Algorithm for Halftoning Image
8pecialty: Computer Application & Tecbnology Name: YuTao
Instructor: Prof. Kong Yue-ping
ABSTR扇CT
刀le images printed on paper 缸e existed in all of our have done a gr阅t favor to share municate the information,and they also have been persecuted
by the illegal ∞py more and more. 80 the author and bookrnan's profits 缸e lost badly.
As a new tecbnique of copyright protection for printed images,the waterrnarking can solve the problem effectively.
Halftoning is an especial technique in printer,which can convert digi创 con-tone
images with n-level grayscale into special binary images. The watermark is embedded into halftoning image can resist the process of printing,scanning and cropping attacks.
Having analyzed the properties of the halftoning edge,texture area,smooth area and human vision system,the two kinds of watermarking algorithms for halftoning image are proposed. The first one has embedded watermark into halftoning image b部ed on the edge and model in the pr,∞ess of halftoning. The second one h出 segmented the halftoning image into many blocks,and the watennark is embedded
with di他rent rules which are d民ided by the property of each block. A large amount of experimen岱 show the two algorithms have good performance on invisibility and
robustness if only embed appropriate watennark into the halftoning image. And the
watermark can be correctly extracted when the watermarked image is printed and attacked by random marking ,crop