Method and apparatus for reading machine-readable symbols having surface or optical distortions

A method of sampling information of a distorted image of machine-readable visual indicia within a reader image generated and stored by an indicia reader, the machine-readable visual indicia in its undistorted form having a plurality of information bearing indicia extending and decodable along at least one axis, and the plurality of information bearing indicia having a plurality of edges between the information bearing indicia and areas formed therebetween, the method comprising the steps of:

• identifying a starting point proximate to an information bearing indicia of the distorted image of the machine-readable visual indicia;
• identifying at least some edges of the information bearing indicia based on the starting point;
• selecting at least one point on each identified edge;
• defining at least one path extending between each corresponding point of each edge;
• and
• sampling the information bearing indicia along the at least one path.

A method of analyzing a distorted image of a data collection symbol stored within a two-dimensional image generated and stored by a symbol reader, the symbol in its undistorted form having an array of substantially parallel rectangular bars and spaces between the bars that encode data, the bars and spaces being arranged along at least one dimension, the symbol being distorted in three-dimensions, the method comprising the steps of:

• locating a bar or space of the distorted two-dimensional image of the data collection symbol;
• identifying an edge of the bar or space;
• repeating the steps of locating a bar or space and identifying an edge until at least some of the edges of the bars and spaces in the data collection symbol have been identified;
• selecting a plurality of points on each identified edge;
• defining a plurality of segments extending between each corresponding point of each edge;
• and
• defining a plurality of planar areas for bar or space, each planar area defined by a pair of the plurality of segments and portions of adjacent identified edges.

An apparatus for decoding a machine-readable symbol representing encoded information, the symbol including an array of shapes and spaces between each shape that encode data, the shapes and spaces being arranged along at least one axis, the apparatus comprising:

• an image sensor that receives light reflected from the symbol and that produces an output signal therefrom that represents a distorted image of the shapes and spaces comprising the symbol;
• a storage device for storing the output signal of the distorted image of the shapes and spaces;
• and
• a processor for processing a stored signal and producing a signal indicative of the information encoded in the symbol, wherein a processor (a) identifies edges of the shapes in the symbol, (b) selects at least one point on each edge, (c) defines at least one path extending between each corresponding point of each edge, (d) samples the bars and spaces along the at least one path;
• and (e) decodes the data in the symbol based on the sampled bars and spaces along the at least one path.

A method of sampling information of a distorted image of machine-readable indicia within a reader image generated and stored by an indicia reader, the machine-readable visual indicia in its undistorted form having a plurality of information bearing indicia extending and decodable along at least one axis, the method comprising the steps of:

• identifying a starting point proximate to an information bearing indicia of the distorted image of the machine-readable visual indicia;
• identifying a curve extending through at least some of the information bearing indicia based on the starting point;
• selecting at least one point on each identified curve;
• defining at least one path extending between each corresponding point of each identified curve;
• and
• sampling the information bearing indicia along the at least one path.