Rotation-invariant pattern matching using wavelet decomposition

In this paper, we propose a wavelet decomposition approach for rotation-invariant template matching. In the matching process. we first decompose an input image into different multi-resolution levels in the wavelet-transformed domain, and use only the pixels with high wavelet coefficients in the decomposed detail subimage at a lower resolution level to compute the normalized correlation between two compared patterns. To make the matching invariant to rotation, we further use the ring-projection transform, which is invariant to object orientation, to represent an object pattern in the detail subimage. The proposed method significantly reduces the computational burden of the traditional pixel-by-pixel matching. Experimental results on a variety of real images have shown the efficacy of the proposed method. (C) 2002 Elsevier Science B.V. All rights reserved.