评价数字水印相似程度的公式分析及改进

当前常见的作为评价数字水印相似程度公式的归一化相关值, 在表示提取出的水印与原始水印反面相似时存在很大的不足. 为此, 本文首先对常见的几种归一化相关值公式进行了分析, 然后继承这些公式的合理性和有效性, 克服这些公式的不足, 构造出了一个新的能更科学、合理和有效地评价数字水印相似程度的公式, 本文称之为两极化相关值. 最后对两极化相关值与归一化相关值进行了对比实验, 实验结果验证了两极化相关值的科学性、合理性和有效性.

Analysis and Improvement of Formulas for Evaluating Similarity Degree of Digital Watermarks

Currently familiar formulas called normalized cor- relation,which are used for evaluating the similarity degree of digital watermarks,showed their big shortage when expressing the similarity degree of extracted watermark and original wa- termark in inverse similarity.Therefore,in this paper,several common formulas of normalized correlation are analyzed firstly. Then by inheriting the rationality and effectivity of these formu- las,and overcoming the shortage of them,a novel formula named polarized correlation is constructed,which can more scientifi- cally,rationally,and effectively evaluate the similarity degree of digital watermarks.Lastly,contrasting experiments of polarized correlation and normalized correlation are done,and the experi- mental results validate the science,rationality,and effectivity of polarized correlation.