Abstract: The status in quo of capacity theory research of watermarking system is simply reviewed. It is thought as maximum reliable transfer rate of communication model that watermark capacity is researched in fixed channel while carrier is presented. Two scenarios are deeply analyzed with attack behavior or not. Under conditions with embedding and attacking restriction in Euclidean measurement, the relationship between quantity division of n-dimensions nodes and watermark capacity is obtained. The capacity upon threshold can be calculating. At last, the relationship is analyzed between watermark extraction error rate and watermark capacity in attacking scenario.

Key words: digital watermark, capacity theory, n-dimensions space, optimum coding

摘要： 回顾了水印容量研究的现状，认为水印容量是作为通信模型的最大可靠传输率，研究了给定 载体这种固定信道的水印容量，对无攻击和有攻击2种情况作了深入的分析，在欧几里得距 离的嵌入和攻击约束条件下，通过对载体在n维几何空间的变化分布情况，得到空间节 点集合的量化分割与水印容量的关系，从而得到可计算的该载体的容量门限。最后分析了有 攻击情况下水印提取错误率与水印容量的关系。

关键词: 数字水印, 容量理论, n维空间, 最优编码