Patent ID: 11875218
Assignee: DIGIMARC CORPORATION
Field: Computer technology (Electrical engineering)
Classification: CPC G | IPC G

Claim 13:
14. A method employing image data corresponding to a physical object, said physical object having earlier been marked to convey a 2D machine-readable indicia of a first size, said earlier-marked indicia including a payload signal component and a reference signal component, the method comprising the acts:
(a) determining initial spatial correspondence between the image data and the reference signal component of the 2D machine-readable indicia;
(b) selecting a patch of the image data that is smaller than said first size, and correlating the selected patch of the image data with a spatially-corresponding patch of the reference signal component;
(c) perturbing initial spatial correspondence between the image data and the reference signal component, said perturbing changing locations within the reference signal component to which locations in the selected patch of the image data correspond, and performing a further correlation operation based on said perturbed spatial correspondence, yielding a further correlation value associated with said perturbed spatial correspondence;
(d) repeating act (c) one or more further times with differently-perturbed spatial correspondences, yielding one or more still further correlation values, each associated with a differently perturbed spatial correspondence;
(e) identifying one of said correlation values as having a highest absolute value, and determining from a sign of said identified correlation value whether the selected patch of the image data exhibits inversion; and
(f) adjusting the image data to compensate for said determined inversion.