Based on the singularity value of each pixel and its relative height , that is given by computing spectra associated with different kinds of capacities denned from gray levels , edge information of image is gotten according to the modified multifractal spectrum 将混沌理论引入数字水印初始序列的创建中，实现了混沌序列水印在原始图像小波域中的自适应嵌入，从而兼顾了数字水印的不可见性和鲁棒性。
An algorithm of watermark is put forward . it embeds watermark via masking characteristic of human vision texture , luminance and blue channel . this algorithm ensured the invisibility of watermark and demonstrated better robustness in common image processing 4 、给出了一种利用人类视觉纹理、亮度和蓝色通道掩蔽特性嵌入水印的算法，该算法在保证水印不可见性的同时，对常见的图象处理表现出较好的鲁捧性。
Because of the attributes of invisibility , robustness and safety for the imbedded information , it is possible that the quality of the imbedded image is not destroyed after imbedding operation , meanwhile the ascription of copyright of the protected image is still available after some processing 利用数字图像水印技术嵌入的被隐藏信息具有不可见性、鲁棒性和安全性等特点，可以不破坏被保护图像的图像质量，同时使得被保护图像在传播、复制和非法篡改之后仍然能够被判断出其版权归属。
To the common requirement of invisibility of the two , the paper presents a information hiding strategy which first uses cluster analysis methods ( this paper uses k - means algorithm ) to classify the image to get the nature of the image , and then uses one embedding algorithm , accounting the improvement on the conceal effect using image ' s character 接着对信息隐藏技术的两个重要分支隐写术与数字水印技术，阐述其各自特点及异同点，针对二者在不可见性上的共同要求，从利于图像自身的特性增强掩密效果的思路出发，提出先用聚类分析的方法(本文采用了k -均值算法)对图像的像素点进行分类以充分发掘图像自然的内在特性，再结合嵌入算法的信息隐藏策略。
In this algorithm , bss and discrete wavelet transform are combined : binary image is used as watermark and is embedded into the wavelet domain to ensure the robustness and invisibility of watermark ; bss is applied in the extraction of watermark to get the watermark with definite resolution on the condition of lack of source image . it is experimently proved that our blind watermark algorithm based on bss is satisfying 该算法将盲信号分离问题和离散小波变换相结合用于数字图像水印技术：水印嵌入时，以二值图像作为水印，嵌入到被保护图像的小波域中，保证了水印的鲁棒性和不可见性；水印提取时利用盲信号分离算法在没有原始图像的情况下将具有一定分辨率的水印图像提取出来，直观方便。
In order to adapt the scheme to both the color image and the gray image , while embedding the watermarking into the image , the scaling factors are determined by the local luminance feature and texture features of the image . it can improve the embedding strength and the watermarking robustness . from the experimental results , the stego - images are extremely robust to common image processing such as median filter , jpeg compression and denoising after adding the stochastic noises 2 、提出了一种新的基于小波变换和纹理特征的数字水印算法，该算法依据从图像小波域提取出的纹理特征来选取水印的嵌入位置，较好地利用了图像的纹理区域，既能掩蔽较多的噪声，又能较好地抵抗jpeg压缩等一般性攻击，调节了数字水印技术中存在的不可见性与鲁棒性之间的矛盾。
Database authentication is the process by which the database server establishes the identity of the client , and by extension determines whether the client application ( or the user who runs the client application ) is permitted to connect with the user name that was requested it is the combination of authentication technology and database technology . with the development of the third - party authentication product and cryptosystems , database authentication has a great advancement both in theory and practice . but current database products are purchased from foreign countries , our country ' s information security is unreliable without grasping the key security technologies . it is significant to develop a national database with our own technologies 随着各种第三方认证产品和加密技术的出现，数据库用户认证在理论和实践上都有了长足的进步。但现有的数据库产品大都是国外的产品，安全技术的不可见性使国家的信息安全受到极大威胁。因此，开发具有自主知识产权的国产数据库具有重要的意义。
By studying jpeg compression and hvs theory , watermarking information is embedded in the dct intermediate frequency coefficient part of the image . in order to enhance security level in the data transfers , matrix scrambling algorithm is used . after deeply analyzing the technical characteristics and requirements of image watermarking , two present algorithms are improved to enhance their imperceptibility and robustness , and two dct - based image watermarking algorithms which can be applied to copyright protection are put forward in this paper 通过对jpeg压缩以及人眼视觉系统理论的研究，确定了把水印信息嵌入到图像的离散余弦变换域的中频系数部分；为了加强数据传输时数字水印的安全性，使用了矩阵乱序加密方法；在详细分析数字水印技术特性和需求的基础上，从提高水印的不可见性和鲁棒性出发，对现有算法进行改进，提出了两个新的离散余弦变换域数字水印算法。
Because the watermark embedding and the noisy channel were directly related to the codeword index order in the model , at the same time deciding the codeword index was a np - hard problem typically , so the ant colony algorithm was introduced to optimize it in order to make the bit error rate lower and the embedded watermark more invisible 在该模型中，由于水印嵌入和通道噪声直接与码字索引相关，所以该模型误差由索引值决定，又由于码字索引的确定是np难度问题，故引入蚁群算法对其优化是方便的，优化目标是降低误码率和使不可见性达到最佳。
Experimental results show that the proposed techniques have good imperceptibility and can survive of common image processing operations and jpeg lossy compression with high robustness . the second one considered the watermarking system as a special digital communication system and introduced the ecc as channel coding technique . by using the turbo coding technique , we are able to reduce the watermark bit error rate and improve the robustness of the watermark so as to make counterfeiting attacks more difficult 本文在保证水印不可见性的基础上和载体图像的允许降质范围内，利用rbf神经网络技术实现数字水印信息的最大强度嵌入以增强数字水印抵御各种恶意攻击的稳健性;在通信论和信息论模型基础上，引入ecc (差错控制编码)技术降低水印的误码率，使得提取水印信息更加可靠，使可能的水印攻击变得更加困难，从而获得更好的水印稳健性和可靠性。
