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Affine Invariant Ring Fourier Descriptors

The traditional affine-invariant Fourier descriptor is contour-based. It can not be applied to objects with several components. In this paper, a region-based Affine Invariant Ring Fourier Descriptor (AIRFD) is put forward to extract affine invariant features. A set of affine invariant closed curves is constructed from the object. Prior to the extraction of features, the derived closed curves are parameterized to establish a one-to-one correspondence between points on the original closed curves and points on the closed curves of their affine transformed version. Consequently, these closed curves are put on the image of the image, and pixels on these closed curves are derived. Finally, a Fourier transform is conducted on these pixel series. As a result, AIRFDs are derived. Experimental results show that the proposed method can be used for object classification.