【作者】 鲁英春；

【导师】 王玲；

【作者基本信息】 四川师范大学 ， 计算机软件与理论， 2008， 硕士

【摘要】 数字水印(Digital Watermarking)是目前防伪及信息安全技术领域的重要研究方向,具有安全性、鲁棒性、不可感知性、以及保真性。将数字水印技术应用到包装防伪与认证上,可以克服传统包装防伪技术的缺点,具有其他技术难以替代的优点,其主要表现为:技术独占性;防伪投资小、成本低;技术升级快;技术检测易分辨、易识别、检测提取容易;图像加入水印后,可以在供应链的节点上进行认证,辨别是否是原件的拷贝,防止伪造和产品替换;保密性高等。在已有的研究工作中,水印的嵌入和提取都是基于平面图像处理。对于商品包装图像,水印的检测是直接在商品上进行。由于商品都有各自不同的外形,贴在商品表面的包装图像也就随着商品外形而发生了改变,相对于初始图像,这种变化不再是某种几何变化(如旋转,平移,缩放等),而是一种既有尺度变换又有弯曲变形的不规则变形。这种变形会破坏图像与水印之间的数据同步性,从而影响水印的检测。本文研究内容围绕商品包装图像在水印检测过程中图像会发生变形的问题展开,研究了已有的鲁棒数字水印算法,提出了解决问题的方法。本文的主要工作包括以下几个方面:1.建立商品包装图像的几何模型,提出了包装图像防伪数字水印应满足的基本要求。按照产品设计理论,针对包装物品的外形确定包装图像扭曲的类型,建立相应的几何模型。在几何模型的基础上,构造了酒瓶模型作为研究对象。针对模型包装图像,应用已有的抗几何攻击的水印算法展开实验,提出了包装图像防伪数字水印应满足的要求。2.提出了基于小容量鲁棒性盲数字水印算法。在研究量化水印技术和基于图像内容的水印算法基础上,提出了基于离散小波变换和离散余弦变换的混合水印盲算法,解决了水印图像随商品外形发生变形后水印的提取问题。实验结果表明该算法具有较好的水印不可感知性,且提取效果好,是一种鲁棒性好的盲数字水印算法。3.提出了基于非均值量化系数特征不变的数字水印算法。算法同样适合解决水印图像随商品外形发生弯曲变形后水印的提取问题,同时解决了水印嵌入容量的问题。实验结果表明该算法具有较好的水印不可感知性,且提高了水印嵌入容量,在商品有较大角度偏转和位移的情况仍能正确提取,是一种具有较大容量的盲数字水印算法。更多还原

【Abstract】 Digital Watermarking featuring security, robustness and high fidelity is a new approach to maintain the technique of anti-counterfeiting and information security.The application of Digital Watermarking to the anti-counterfeiting packaging and authentication can remove the flaws in the traditional packaging. It has the advantages of exclusiveness, low cost of investment, speedy upgrade and easy differentiation and check. When the trademark or logo is digitally watermarked, it can be authenticated at the point of the supply chain, where the checking of the authenticity of the product is done and its replacement is prevented, canceling the drawbacks in security.In recent years, Watermarking embedding and collecting are processed on the basis of the plane imaging while the watermark check is directly done on the product.The package image usually changes with that of the external shape of the product. Compared with the initial picture, such a change is no longer a geometrical one like revolution, movement, contraction or amplification, but an irregular one in dimension and shape, which may destroy the synchronism between the picture and the watermark, affecting the check of the watermark.The thesis begins with the distortion issue in watermark checking, investigates the robustness of the past digital watermark algorithm, and provides solutions to the problem of the distortion.The work includes the following:1. Based on the theory of the product package design, categories of the distortion that results from the change of the external shape of the products are established and their corresponding models are made. Among the various models, the model of a wine bottle is chosen as the object of study. Based on the expreiments taken with watermark’s algorithems, the needs are given on contenting the scheme of watermark to anti-counterfeiting packaging.2. A mixed blind algorithm of watermarking based on small volume robustness is offered, which combines discrete wavelet transformation and discrete cosine transformation to solve the problem of the collection of watermark when the distortion occurs with the change of the external shape of the picture. The experimental findings indicate that the algorithm has the features of watermark imperceptibility, good collection and robustness.3. A new digital watermark algorithm based on the stable features of non-equal quantization is proposed, which can be used in solving the problem of collecting and embedding of the watermark when there is a distortion with the change in the picture. The experimental findings indicate that it is a big-volume watermark algorithm, which has a better imperceptibility in the watermark, larger volume in embedding, and is still valid when the product undergoes a big swerve in angle or shift in position.更多还原