Improvement and Invariance Analysis of Pseudo-Zernike Moments
Jiaxiong Peng · 2003
Pseudo-Zernike is a kind of region-based shape descriptor, contour-based shape descriptors, such as curvature descriptors, Fourier descriptors, signature or chain code-based descriptors, are not appropriate for describing shapes consisting of several disjoint regions, since they are often based on a single contour. There is no information redundancy because the bases of pseudo-Zernike moments are orthogonal. The magnitude of pseudo-Zernike moments has rotational invariant property. An image can be better described by a small set of its pseudo-Zernike moments than any other types of moments such as geometric moments, Legendre moments, rotational moments, and complex moments in terms of mean-square error. A relatively small set of pseudo-Zernike moments can characterize the global shape of a pattern effectively. Lower order moments represent the global shape of a pattern and higher order moments represent the detail. Pseudo-Zernike moments do not possess scale invariance. In this paper, we analyze the invariance of pseudo-Zernike moments and present an improved pseudo-Zernike moments that not only have rotation invariance, but also have scale invariance, and the same time, we give part of analysis result. The experimental results show that the improved Zernike moments have better invariant properties than unimproved Zernike moment using as region-based shape descriptor.