Complex moments for the analysis of metal-mechanical parts

Complex moments are usually used to characterize, analyze and extract information from an image. The extracted characteristics can be used in pattern recognition. In this work, the classiOcation of metal-mechanical pieces based on the invariant complex moments in an array of polar pixels is presented. The conventional calculation of complex moments is through the zero-order approximation; the integrals are replaced by summations. In this work we propose the calculation of complex moments using an array of polar pixels, which has the purpose of integrating the kernel of complex moments in an analytical manner and eliminates the geometry error inherent in the computation of complex moments. The proposed method is used to classify metal-mechanical parts that have intrinsically small di§erences between them, such as millimeter screws. Finally, the experimental results of four families of standard screws with a polar pixel scheme and the zero order approximation are presented.