Patent ID: 11868844
Assignee: UNIVERSIDAD DE MURCIA
Field: Computer technology (Electrical engineering)
Classification: CPC G | IPC G

Claim 0:
1. Method for decoding a visual code reproduced on an identification label, comprising
capturing a flat image of the label using an optical sensor;
locating a candidate code in the flat image;
extracting a quadrangular contour of the candidate code;
using the four corners of the quadrangular contour to rectify the candidate code homographically into a rectified quadrangle;
calculating the Discrete Fourier Transform (DFT) of the rectified quadrangle;
extracting from the DFT of the rectified quadrangle c dominant frequency components, both for a first spatial frequency u′ and for a second spatial frequency v′;
seeking an identification among the c dominant frequency components of first spatial frequency u′ and second spatial frequency v′ with c two-dimensional waves from a predetermined collection of two-dimensional waves, each of which being determined by at least two parameters, namely, a first spatial frequency u in a first direction and a second spatial frequency v in a second direction different from the first direction.