[OPTICAL REVIEW Vol. 1, No. 2 (1994) 198-201]

Rotational-Invariant Pattern Recognition Using Circular Harmonic and Optical Wavelet Transform

Tsair-Chun LIANG and Yih-Shyang CHENG

Institute of Optical Sciences, National Central University, Chung-Li, Taoyuan 320, Taiwan, ROC

(Accepted August 26, 1994)

An improved shift- and rotational-invariant filter using wavelet transform and circular harmonic filtering at the same time is proposed. Computer simulation has shown that this is better than using a phase-only circular harmonic filter in peak sharpness, discriminating ability, SNR and tolerance of position error of the filter. Furthermore, this filter possesses moderate diffraction efficiency.

Key words : rotational-invariant pattern recognition, circular harmonic filter, wavelet transform