Subpixel Estimation of the Node Coordinates of Quasiperiodic Textures

An algorithm is proposed to estimate the node coordinates of deformed lattices of quasiperiodic textures with subpixel accuracy. The algorithm consists of two steps. In the first step, the frequency and initial phase vectors of a polyharmonic brightness function model are calculated from the characteristics of spectral outliers of image fragments. The obtained estimates are used to determine the coordinates of the nodes of the local lattice. In the second step, the local lattices are combined into a global lattice for the entire image of the quasi-periodic texture. Using high-accuracy estimates of model parameters from small image fragments ensures stable operation of the algorithm for significant deformations of the lattice and sub-pixel accuracy in estimating the coordinates of its nodes. Results of computer simulation and processing of real halftone images of quasiperiodic textures are given demonstrating the effectiveness of the proposed algorithm.