A method (400) of estimating an orientation angle (β0) of a pattern in an image (405) is described. A complex energy operator is applied to the image (405). The complex energy operator is defined as Ψc{f}=(D{f})2−fD2{f}. A phase component of the result, which is defined as 2β0=arg(Ψc{f}) is determined,...http://www.google.com/patents/US7043082?utm_source=gb-gplus-sharePatent US7043082 - Demodulation and phase estimation of two-dimensional patterns
