초록 ▼

A method and system for decoding a two-dimensional optical symbol in the spatial domain. The system determines the orientation of an imaged symbol in the spatial domain by using a template to derive a correlation coefficient between radially adjacent signals at a given angle of the template and comp

A method and system for decoding a two-dimensional optical symbol in the spatial domain. The system determines the orientation of an imaged symbol in the spatial domain by using a template to derive a correlation coefficient between radially adjacent signals at a given angle of the template and comparing the correlation coefficients as the template is rotated with respect to the image. The angle of the highest correlation coefficient corresponds to the orientation of a set of symbol axes which include contiguous elements whose centers are collinear. The system then locates each individual information-encoded element of the symbol by using segments of the symbol defined by the axes, first adjusting for each segment the axis position and element size for subsequent determination of the location of all elements for decoding. The system is disclosed as applied to a symbol constructed as a matrix of hexagonal information-encoding elements arranged in a square, with, at its center, an acquisition target consisting of six concentric rings of alternating light and dark reflectivity.

대표청구항 ▼

[ What is claimed is:] [3.] An image processor for locating in an image one or more sets of contiguous elements whose centers are collinear, comprising:a sampling template for plotting data acquisition locations in said image, said template having two sequences of data acquisition points, each seque

[ What is claimed is:] [3.] An image processor for locating in an image one or more sets of contiguous elements whose centers are collinear, comprising:a sampling template for plotting data acquisition locations in said image, said template having two sequences of data acquisition points, each sequence spaced along one of two parallel lines spaced apart by a distance shorter than a width of each of said elements measured perpendicular to the parallel lines, the sequences together defining pairs of points having a first point positioned on one of the parallel lines across from a second point of said pair on the other parallel line;a positioner for positioning said template on said image and for moving said sampling template into varying orientations with respect to said image;a comparator for comparing gray scale intensities of the first points of said pairs to gray scale intensities of respective second points of said pairs to determine a correlation factor between said sequences of said first points and said second points, representing a measure of the pair-by-pair difference in gray scale value between the two sequences of points; anda finder for identifying said one or more set of collinear elements by finding one or more template positions associated with characteristic values of said correlation factor.