A logarithmic harmonic filter can detect objects at different projection angles. The Mexican-hat wavelet function can extract edges of equal width for objects, regardless of their sizes. Hence incorporating wavelet filtering in the logarithmic harmonic filter can improve its performance. The theory is presented together with computer simulation. Finally, an experiment using a joint transform correlator is presented to verify the capability of the proposed filter.
© 2001 Optical Society of America
(070.4550) Fourier optics and signal processing : Correlators
(070.5010) Fourier optics and signal processing : Pattern recognition
(070.6110) Fourier optics and signal processing : Spatial filtering
(100.7410) Image processing : Wavelets
Yih-Shyang Cheng and Hui-Chi Chen, "Projection-Invariant Pattern Recognition with Logarithmic Harmonic Function and Wavelet Transform," Appl. Opt. 40, 4661-4666 (2001)