Optical reader using distance map decoding
First Claim
1. An optical reader for decoding an encoded candidate character of a symbology, the optical reader comprising:
- a lens system for focusing an illuminated encoded candidate character at a plane of focus;
an optical sensor having as an input detected light intensity corresponding to illumination reflected from the encoded candidate character, and having as an output an electrical signal encoding information representative of the encoded candidate character;
wherein the optical reader accesses a distance map comprising a seed codeword and a plurality of seed distance values, each seed distance value comprising a computed distance from the seed codeword to a character of the symbology;
wherein the optical reader computes a candidate distance value from the seed codeword to the encoded candidate character;
wherein the optical reader compares the encoded candidate character to a subset of the characters of the symbology, the subset comprising characters of the symbology having seed distance values within a specified range of the candidate distance value.
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Abstract
A method for decoding an encoded candidate character of a symbology is provided that includes the steps of providing a plurality of valid barcode characters of a symbology having n elements, generating a seed codeword comprising n elements, computing a seed distance value from the seed codeword to each character in the symbology, generating a distance map comprising each character in the symbology and the associated computed seed distance value, and arranging the plurality of seed distance values into a plurality of bins. Each bin contains a subset of the characters in the symbology. The method includes the steps of selecting a candidate barcode character for decoding, computing a candidate distance value from the candidate barcode character to the seed codeword, identifying the bin containing the candidate distance value, and comparing the candidate barcode character with the valid barcode characters in the bin having the candidate distance value.
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Citations
25 Claims
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1. An optical reader for decoding an encoded candidate character of a symbology, the optical reader comprising:
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a lens system for focusing an illuminated encoded candidate character at a plane of focus; an optical sensor having as an input detected light intensity corresponding to illumination reflected from the encoded candidate character, and having as an output an electrical signal encoding information representative of the encoded candidate character; wherein the optical reader accesses a distance map comprising a seed codeword and a plurality of seed distance values, each seed distance value comprising a computed distance from the seed codeword to a character of the symbology; wherein the optical reader computes a candidate distance value from the seed codeword to the encoded candidate character; wherein the optical reader compares the encoded candidate character to a subset of the characters of the symbology, the subset comprising characters of the symbology having seed distance values within a specified range of the candidate distance value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method for decoding an encoded candidate character of a symbology, the method comprising the steps of:
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providing a plurality of valid barcode characters of a symbology, each barcode character having n elements in conformance with the symbology; generating a seed codeword comprising n elements; computing a seed distance value from the seed codeword to each character in the symbology; generating a distance map comprising each character in the symbology and the associated computed seed distance value; arranging the plurality of seed distance values into a plurality of bins, each bin containing a subset of the characters in the symbology; selecting a candidate barcode character for decoding, the character comprising n elements; computing a candidate distance value from the candidate barcode character to the seed codeword; identifying the bin containing the candidate distance value; and attempting to decode the candidate barcode character by comparing the candidate barcode character with the valid barcode characters in the bin having the candidate distance value. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
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Specification