\input zb-basic \input zb-ioport \iteman{io-port 06094832} \itemau{Yu, Ying; Dong, Cai-lin} \itemti{Invariant feature extraction of amount chinese characters based on ridgelet transform.} \itemso{J. Comput. Appl. 31, No. 12, 3403-3406 (2011).} \itemab Summary: To meet the requirements of multi-directional choice, a new approach to the invariant feature extraction of handwritten amount Chinese characters was raised, with Ridgelet transform as its foundation. As far as this approach is concerned, first of all, the original images would be rotated to the Radon circular shift by means of Radon transform. On the basis of the characteristic that Fourier transform is row shift invariant, then, the one-dimensional Fourier transform would be adopted in Radon field to gain the conclusion that magnitude matrixes bear the rotation-invariance as a typical feature, which was pretty beneficial to the invariant feature extraction of rotation. When this was done, one-dimensional wavelet transform would be carried out in the direction of rows, thus achieving perfect choice of frequency, which made it possible to extract the features of sub-line in the appropriate frequencies. Finally, the average values, standard deviations and the energy values would form the feature vector which was extracted from the Ridgelet sub-bands. The approaches mentioned in the paper could satisfy the requirements from the form automatic processing on the recognition of handwritten amount Chinese characters. \itemrv{~} \itemcc{} \itemut{ridgelet; multiresolution analysis; invariance; feature extraction; handwritten amount Chinese characters recognition} \itemli{} \end