小波域内图象零水印技术的研究

为了在保证图象质量的前提下实施图象的版权保护，提出了一种图象零水印方法．该方法改变了传统的向原始图象中嵌入水印信息来实现版权保护的做法，采用从图象中抽取水印信息的方法来实现这一功能，其核心思想是：恰当选取图象小波变换的系数，然后把它作为原始图象的基本信息进行定位和管理，当对待认证图象进行认证时，用同样的方法提取该认证图象的信息，并对这些信息进行分析和检测，从而判定该图象的版权和所有权．通过实验证明，这种方法具有无失真、鲁棒性好、简单易行及可操作性强等优点．最后对该方法进行了推广，使它不但可以从原图象中提取水印，而且可以在图象外部加载水印，该方法既能满足图象认证的需要，又能用来进行数据隐藏．

Study on the Method of Image Non-watermark in DWT Domain

In order to protect the copyright of the image in the condition of the image quality,It brings forward a kind of the image non watermarking method. It introduces the non watermarking scheme,then it discusses the concrete process of this scheme at length. This method changes the traditional doings that the copyright of the image is protected by embedding the watermarking into the image to the method that the watermarking is drew out from the image, The central idea of this method is: the image wavelet coefficients are selected correctly firstly, then they are located and managed as the basic informations of the image.When the authentication image is to be identified,the same process is done to draw the informations out from the authentication image and those informations will be analyzed and detected to judged the copyright and the ownership of the image.It demonstrates this method is right by some tests. These tests prove that the method could make image distortion free and be robust,simple,easy to use. Lastly, it makes the method broaden and watermarking can be drew out from the image and embedded outside the image.This method not only can satisfy the need of the image authentication,but also can be used to hide the data.