Method and apparatus for decoding bar code images using multi-order feature vectors

Claim 1

A method for decoding a pixel image representative of a bar code symbol comprising a plurality of encoded character values each of which corresponds to one of a plurality of prototype bar patterns, each of said prototype bar patterns having a set of predetermined prototype bar width feature values uniquely associated therewith, comprising the steps of: (A) determining a first set of bar width information estimates from said pixel image, said first set of bar width information estimates being representative of an encoded character value stored in said bar code symbol; (B) determining a second set of bar width information estimates from said pixel image, said second set of bar width information estimates being of a different order than said first set of bar width information estimates, said second set of bar width information estimates being representative of said encoded character value stored in said bar code symbol; (C) combining said first and second sets of bar width information estimates to form a multi-order set of bar width information estimates; (D) comparing said multi-order set of bar width estimates to a selected set of predetermined prototype bar width feature values; (E) determining in accordance with said comparison whether said encoded character value stored in said bar code symbol corresponds to said selected set of predetermined prototype bar width information values; and (F) decoding said encoded character value in accordance with the result of step (E).

Claim 2

A method for decoding a pixel image representative of a bar code symbol comprising a plurality of encoded character values each of which corresponds to one of a plurality of prototype bar patterns, each of said prototype bar patterns having a set of predetermined prototype bar width feature values uniquely associated therewith, comprising the steps of: (A) determining a first set of bar width information estimates from said pixel image, said first set of bar width information estimates being representative of an encoded character value stored in said bar code symbol; (B) determining a second set of bar width information estimates from said pixel image, said second set of bar width information estimates being of a different order than said first set of bar width information estimates, said second set of bar width information estimates being representative of said encoded character value stored in said bar code symbol; (C) combining said first and second sets of bar width information estimates to form a multi-order set of bar width information estimates; (D) comparing said multi-order set of bar width estimates to a selected set of predetermined prototype bar width feature values; (E) determining in accordance with said comparison whether said encoded character value stored in said bar code symbol corresponds to said selected set of predetermined prototype bar width information values; and (F) decoding said encoded character value in accordance with the result of step (E).

Claim 10

A method for decoding a pixel image representative of a bar code symbol comprising a plurality of encoded character values each of which corresponds to one of a plurality of prototype bar patterns, each of said prototype bar patterns having a set of predetermined prototype bar width feature values associated uniquely therewith, comprising the steps of: (A) determining a set of bar width information estimates from said pixel image, at least one of said bar width information estimates being representative of the width of an interval spanning three or more edge transitions in said bar code symbol, wherein each of said edge transitions corresponds to an edge of a bar in said bar code symbol; (B) selecting a prototype bar pattern for comparison; (C) comparing said set of bar width information estimates to a selected set of predetermined prototype bar width feature values to determine a plurality of individual difference values, wherein each of said individual difference values represents the difference between one of said bar width information estimates and a corresponding predetermined prototype bar width feature value, and wherein said selected set of predetermined prototype bar width feature values corresponds to said prototype bar pattern selected in step (B); (D) calculating a composite distance value corresponding to said prototype bar pattern selected in step (B) in accordance with each of said individual difference values; (E) generating a plurality of composite distance values corresponding to a plurality of differing prototype bar patterns by repeating steps (B)-(D); (F) selecting from said plurality of composite distance values the minimum composite distance value; (G) determining that said bar code symbol includes said prototype bar pattern associated with said selected minimum composite distance value; and (H) decoding said bar code symbol in accordance with the result of step (G).

Claim 11

A method for decoding a pixel image representative of a bar code symbol comprising a plurality of encoded character values each of which corresponds to one of a plurality of prototype bar patterns, each of said prototype bar patterns having a set of predetermined prototype bar width feature values associated uniquely therewith, comprising the steps of: (A) determining a set of bar width information estimates from said pixel image, at least one of said bar width information estimates being representative of the width of an interval spanning three or more edge transitions in said bar code symbol, wherein each of said edge transitions corresponds to an edge of a bar in said bar code symbol; (B) selecting a prototype bar pattern for comparison; (C) comparing said set of bar width information estimates to a selected set of predetermined prototype bar width feature values to determine a plurality of individual difference values, wherein each of said individual difference values represents the difference between one of said bar width information estimates and a corresponding predetermined prototype bar width feature value, and wherein said selected set of predetermined prototype bar width feature values corresponds to said prototype bar pattern selected in step (B); (D) calculating a composite distance value corresponding to said prototype bar pattern selected in step (B) in accordance with each of said individual difference values; (E) generating a plurality of composite distance values corresponding to a plurality of differing prototype bar patterns by repeating steps (B)-(D); (F) selecting from said plurality of composite distance values the minimum composite distance value; (G) determining that said bar code symbol includes said prototype bar pattern associated with said selected minimum composite distance value; and (H) decoding said bar code symbol in accordance with the result of step (G).

Claim 15

An apparatus for decoding a pixel image representative of a bar code symbol comprising a plurality of encoded character values each of which corresponds to one of a plurality of prototype bar patterns, each of said prototype bar patterns having a set of predetermined prototype bar width feature values uniquely associated therewith, comprising: (A) first determining means for determining a first set of bar width information estimates from said pixel image, said first set of bar width information estimates being representative of an encoded character value stored in said bar code symbol; (B) second determining means for determining a second set of bar width information estimates from said pixel image, said second set of bar width information estimates being of a different order than said first set of bar width information estimates, said second set of bar width information estimates being representative of said encoded character value stored in said bar code symbol;. (C) means for combining said first and second sets of bar width information estimates to form a multi-order set of bar width information estimates; (D) a comparator for comparing said multi-order set of bar width estimates to a selected set of predetermined prototype bar width feature values; (E) character determining means for determining in accordance with the output of said comparator whether said encoded character value stored in said bar code symbol corresponds to said selected set of predetermined prototype bar width information values; and (F) decoding means for decoding said encoded character value in accordance with the output of said character determining means.

Claim 16

An apparatus for decoding a pixel image representative of a bar code symbol comprising a plurality of encoded character values each of which corresponds to one of a plurality of prototype bar patterns, each of said prototype bar patterns having a set of predetermined prototype bar width feature values uniquely associated therewith, comprising: (A) first determining means for determining a first set of bar width information estimates from said pixel image, said first set of bar width information estimates being representative of an encoded character value stored in said bar code symbol; (B) second determining means for determining a second set of bar width information estimates from said pixel image, said second set of bar width information estimates being of a different order than said first set of bar width information estimates, said second set of bar width information estimates being representative of said encoded character value stored in said bar code symbol;. (C) means for combining said first and second sets of bar width information estimates to form a multi-order set of bar width information estimates; (D) a comparator for comparing said multi-order set of bar width estimates to a selected set of predetermined prototype bar width feature values; (E) character determining means for determining in accordance with the output of said comparator whether said encoded character value stored in said bar code symbol corresponds to said selected set of predetermined prototype bar width information values; and (F) decoding means for decoding said encoded character value in accordance with the output of said character determining means.

Claim 24

An apparatus for decoding a pixel image representative of a bar code symbol comprising a plurality of encoded character values each of which corresponds to one of a plurality of prototype bar patterns, each of said prototype bar patterns having a set of predetermined prototype bar width feature values associated uniquely therewith, comprising: (A) first determining means for determining a set of bar width information estimates from said pixel image, at least one of said bar width information estimates being representative of the width of an interval spanning three or more edge transitions in said bar code symbol, wherein each of said edge transitions corresponds to an edge of a bar in said bar code symbol; (B) a selector for selecting a prototype bar pattern for comparison; (C) a comparator for comparing said set of bar width information estimates to a selected set of predetermined prototype bar width feature values to determine a plurality of individual difference values, wherein each of said individual difference values represents the difference between one of said bar width information estimates and a corresponding predetermined prototype bar width feature value, and wherein said selected set of predetermined prototype bar width feature values corresponds to said prototype bar pattern selected by said selector; (D) means for calculating a composite difference value corresponding to said selected prototype bar pattern in accordance with each of said individual difference values; (E) means for generating a plurality of composite difference values corresponding to a plurality of differing prototype bar patterns; (F) a selector for selecting a minimum composite distance value from said plurality of composite difference values; (G) second determining means for determining that said bar code symbol includes said prototype bar pattern associated with said minimum composite distance value; and (H) a decoder for decoding said bar code symbol in accordance with the output of said second determining means.

Claim 25

An apparatus for decoding a pixel image representative of a bar code symbol comprising a plurality of encoded character values each of which corresponds to one of a plurality of prototype bar patterns, each of said prototype bar patterns having a set of predetermined prototype bar width feature values associated uniquely therewith, comprising: (A) first determining means for determining a set of bar width information estimates from said pixel image, at least one of said bar width information estimates being representative of the width of an interval spanning three or more edge transitions in said bar code symbol, wherein each of said edge transitions corresponds to an edge of a bar in said bar code symbol; (B) a selector for selecting a prototype bar pattern for comparison; (C) a comparator for comparing said set of bar width information estimates to a selected set of predetermined prototype bar width feature values to determine a plurality of individual difference values, wherein each of said individual difference values represents the difference between one of said bar width information estimates and a corresponding predetermined prototype bar width feature value, and wherein said selected set of predetermined prototype bar width feature values corresponds to said prototype bar pattern selected by said selector; (D) means for calculating a composite difference value corresponding to said selected prototype bar pattern in accordance with each of said individual difference values; (E) means for generating a plurality of composite difference values corresponding to a plurality of differing prototype bar patterns; (F) a selector for selecting a minimum composite distance value from said plurality of composite difference values; (G) second determining means for determining that said bar code symbol includes said prototype bar pattern associated with said minimum composite distance value; and (H) a decoder for decoding said bar code symbol in accordance with the output of said second determining means.