以分数相关为基础的微小差异图样的识别

光学图样识别(OPR)由光学相关来实现，传统的光学相关通过两物体相关峰的尖锐度来判断两物体的相似程度。分数傅里叶变换同时包含了空间域和空间频率域信息，分数相关也可以用于光学图样识别。针对传统相关难以识别微小差异图样的缺点，将分数傅里叶变换和分数相关引入差异相关系统，提出了一种基于分数相关的识别方法。给出了实现这一方法的光电混合系统。计算机模拟处理的结果表明，通过调节分数傅里叶变换的级次，该方法不仅能有效地识别与参考图样有微小差异的图样，而且能提供差异的位置信息。随着分数相关的级次渐变为0，得到的分数差异相关峰逐渐退化为两信号之间的差异；随着分数相关级次渐变为1，分数差异相关渐变为差异相关的结果。

Recognition of Images with Small Differences Based on Fractional Correlation

The optical pattern recognition is realized by optical correlation, the traditional optical correlation judge the similarity degree of two images by their correlation peak. The fractional Fourier transform contains the spatial information and the spatial-frequency information simultaneously. The fractional correlation can be used to optical pattern recognition too. To overcome the defect that the traditional optical correlator can not recognize images with small differences, a new method based on the fractional correlation was proposed. The theory of the photoelectric hybrid system for realizing this method is given. The simulated results showed that by adjusting the fractional order p, the correlator can not only recognize nearly identical images efficiently, but also provide the position information of differences. As the fractional order p approach zero, the fractional difference correlation peak became to the difference of two images; as the fractional order p approach one the result is the same as the result of difference correlation.