[OPTICAL REVIEW Vol. 2, No. 4 (1995) 266-269]

Shift, Rotation and Limited Scale Invariant Pattern Recognition Using Synthetic Discriminant Functions

Hon-Fai YAU,1 Yueh OUYANG1 and Sha-Wei WANG2

1Institute of Optical Sciences, National Central University, Chung-Li Taoyuen 325, Taiwan, R.O.C., 2Chun Shan Institute of Science and Technology, Taoyuan, Taiwan, R.O.C.

(Received February 14, 1995; Accepted May 16, 1995)

Making use of the idea of synthetic discriminant functions (SDF), a simple way to synthesize a shift, rotation and limited size correlation filter is proposed. The SDF is synthesized by superimposing four 2nd order circular harmonics of a training reference pattern in 4 different sizes. Computer simulation experiments have shown that the filter is indeed shift, full rotation and limited size invariant over a size range from 1 to 1.82. The invariant range can be increased if more training patterns are used.

Key words : pattern recognition, shift, rotation and limited size invariant, synthetic discriminant functions, circular harmonic function