闭环图象数字水印技术

为了使数字水印更鲁棒，更实用，通过对水印的嵌入过程及其性能的分析，提出了一种新的图象数字水印技术－闭环数字水印技术，并给出了小波域上的一种实现方法，该闭环水印技术的特点是利用水印的检测性能来不断地调整水印的嵌入，如果检测 能满足某种检测要求或者水印的嵌入已经影响了图象的质量，则可通过调整水印嵌入的强度或者通过调整水印来达到最佳嵌入，同时证明了所提出的闭环水印系统的收敛性，并对检测过程中似然函数的分布规律进行了具体分析，进而推导出两种假设检验情况下，似然函数的均值与方差，以及正确检测概率和错误报警概率的求解公式，其可作为闭环系统检测性能的判决条件，实验结果证明，该数字水印技术优于传统的水印嵌入方法。

Image Closed Loop Digital Watermarking Technique

Combining the embedding process with the performance analysis, this paper presents a new image digital watermarking technique, the closed loop digital watermarking in order to make the technique more robust and utility, and gives an implementation approach in wavelet domain. The embedding process is modified continuously according to the results of the performance analysis of watermarking embedding process. If the watermarking can not meet the requirements of detection process or the embedded watermark renders visual artifact of image, the embedded intensity of watermark or watermark itself is modified so as to obtain optimal embedding effect. The convergence of the closed loop techniques is proved. In the performance analysis, the distribution of likelihood function is analyzed, and the mean and the variance of likelihood function in two hypothesis tests and their relationship are deduced. The probabilities of false alarm and detection are also given which are used as the performance measures for the closed loop system. The conclusions are approved by experimental results that this closed loop watermarking technique takes advatage of traditional methods.