Method and system for bar code acquisition

Claim 1

A method of determining a location and orientation of a linear bar code symbol encoded in one direction and located in an image field, said image field being represented as a plurality of pixels having associated grey levels, and the pixels being organized into a plurality of windows, the method comprising the steps of: analyzing the grey levels of the pixels to determine a subset of said plurality of windows which contain part of the bar code symbol; and determining the direction in which the bar code symbol is encoded based on the subset of windows determined to contain part of the bar code symbol, wherein the step of analyzing the grey levels of the pixels includes the steps of: selecting from the plurality of windows a set of windows comprising candidates for containing the bar code symbol; and examining the candidates to eliminate ones of the candidates which do not contain a part of the bar code symbol, and wherein the step of selecting from the plurality of windows includes the steps of: determining a middle grey level for each of the windows as an average of the grey levels of a brightest pixel and a darkest pixel for each window; determining a balance figure for each of the windows from a magnitude of a difference between a number of pixels having a grey level higher than the middle grey level and a number of pixels having a grey level lower than the middle grey level; and determining that the windows with balance figures greater than a predetermined threshold are not candidates for containing the bar code symbol.

Claim 2

A method of determining a location and orientation of a linear bar code symbol encoded in one direction and located in an image field, said image field being represented as a plurality of pixels having associated grey levels, and the pixels being organized into a plurality of windows, the method comprising the steps of: analyzing the grey levels of the pixels to determine a subset of said plurality of windows which contain part of the bar code symbol; and determining the direction in which the bar code symbol is encoded based on the subset of windows determined to contain part of the bar code symbol, wherein the step of analyzing the grey levels of the pixels includes the steps of: selecting from the plurality of windows a set of windows comprising candidates for containing the bar code symbol; and examining the candidates to eliminate ones of the candidates which do not contain a part of the bar code symbol, and wherein the step of selecting from the plurality of windows includes the steps of: determining a middle grey level for each of the windows as an average of the grey levels of a brightest pixel and a darkest pixel for each window; determining a balance figure for each of the windows from a magnitude of a difference between a number of pixels having a grey level higher than the middle grey level and a number of pixels having a grey level lower than the middle grey level; and determining that the windows with balance figures greater than a predetermined threshold are not candidates for containing the bar code symbol.

Claim 12

An apparatus for determining a location and orientation of a linear bar code symbol encoded in one direction and located in an image field, said image field being represented as a plurality of pixels having associated grey levels, and the pixels being divided into a plurality of windows, the apparatus comprising: means for selecting from the plurality of windows a set of windows comprising candidates for containing the bar code symbol; means for forming the candidates into clusters of contiguous candidates; means for eliminating candidates formed in any cluster having fewer candidates than a predetermined number; and means for determining the direction in which the bar code symbol is encoded based on the remaining candidates, wherein the means for selecting includes: means for determining a middle grey level for each of the windows as an average of the grey levels of a brightest pixel and a darkest pixel for each window; means for determining a balance figure for each of the windows from a magnitude of a difference between a number of pixels having a grey level higher than the middle grey level and a number of pixels having a grey level lower than the middle grey level; and means for determining that the windows with balance figures greater than a predetermined threshold are not candidates for containing the bar code symbol.

Claim 13

An apparatus for determining a location and orientation of a linear bar code symbol encoded in one direction and located in an image field, said image field being represented as a plurality of pixels having associated grey levels, and the pixels being divided into a plurality of windows, the apparatus comprising: means for selecting from the plurality of windows a set of windows comprising candidates for containing the bar code symbol; means for forming the candidates into clusters of contiguous candidates; means for eliminating candidates formed in any cluster having fewer candidates than a predetermined number; and means for determining the direction in which the bar code symbol is encoded based on the remaining candidates, wherein the means for selecting includes: means for determining a middle grey level for each of the windows as an average of the grey levels of a brightest pixel and a darkest pixel for each window; means for determining a balance figure for each of the windows from a magnitude of a difference between a number of pixels having a grey level higher than the middle grey level and a number of pixels having a grey level lower than the middle grey level; and means for determining that the windows with balance figures greater than a predetermined threshold are not candidates for containing the bar code symbol.

Claim 14

A system for scanning a bar code symbol on a surface of an object, comprising: means for obtaining a low-resolution image representing a surface of an object, the image represented as a plurality of pixels having associated grey levels; means for processing said low-resolution image to determine a location and orientation of a bar code symbol, based upon grey levels of the pixels; means for scanning said bar code symbol on said surface of said object to read information from said bar code symbol; and means for decoding said information read from said bar code symbol, wherein the processing means includes: means for dividing the low-resolution image into a plurality of windows; means for determining a subset of windows containing the bar code based upon grey levels of the pixels as being candidates for containing the bar code, means for forming the candidates into clusters of contiguous candidates; means for eliminating candidates formed in any cluster having fewer candidates than a predetermined number; and means for determining the location and the orientation of the bar code symbol based upon the remaining candidates, wherein the means for determining a subset of windows includes: means for determining a middle grey level for each of the windows as an average of the grey levels of a brightest pixel and a darkest pixel for each window; means for determining a balance figure for each of the windows from a magnitude of a difference between a number of pixels having a grey level higher than the middle grey level and a number of pixels having a grey level lower than the middle grey level; and means for determining that the windows with balance figures greater than a predetermined threshold are not candidates for containing the bar code symbol.

Claim 15

A system for scanning a bar code symbol on a surface of an object, comprising: means for obtaining a low-resolution image representing a surface of an object, the image represented as a plurality of pixels having associated grey levels; means for processing said low-resolution image to determine a location and orientation of a bar code symbol, based upon grey levels of the pixels; means for scanning said bar code symbol on said surface of said object to read information from said bar code symbol; and means for decoding said information read from said bar code symbol, wherein the processing means includes: means for dividing the low-resolution image into a plurality of windows; means for determining a subset of windows containing the bar code based upon grey levels of the pixels as being candidates for containing the bar code, means for forming the candidates into clusters of contiguous candidates; means for eliminating candidates formed in any cluster having fewer candidates than a predetermined number; and means for determining the location and the orientation of the bar code symbol based upon the remaining candidates, wherein the means for determining a subset of windows includes: means for determining a middle grey level for each of the windows as an average of the grey levels of a brightest pixel and a darkest pixel for each window; means for determining a balance figure for each of the windows from a magnitude of a difference between a number of pixels having a grey level higher than the middle grey level and a number of pixels having a grey level lower than the middle grey level; and means for determining that the windows with balance figures greater than a predetermined threshold are not candidates for containing the bar code symbol.

Claim 16

A method of determining a location and orientation of a linear bar code symbol encoded in one direction and located in an image field, said image field being represented as a plurality of pixels having associated grey levels, and the pixels being organized into a plurality of windows, the method comprising the steps of: analyzing the grey levels of the pixels to determine a subset of said plurality of windows which contain part of the bar code symbol; and determining the direction in which the bar code symbol is encoded based on the subset of windows determined to contain part of the bar code symbol, wherein the step of analyzing the grey levels of the pixels includes the steps of: selecting from the plurality of windows a set of windows which are candidates for containing the bar code symbol; and examining the candidates to eliminate ones of the candidates which do not contain a part of the bar code symbol, and wherein the step of examining the candidates includes the steps of: forming the remaining candidates into clusters of contiguous candidates; and eliminating candidates formed in any cluster which is smaller than a predetermined size, wherein the step of selecting from the plurality of windows includes the steps of: determining a middle grey level for each of the windows as an average of the grey levels of a brightest pixel and a darkest pixel for each window; determining a balance figure for each of the windows from a magnitude of a difference between a number of pixels having a grey level higher than the middle grey level and a number of pixels having a grey level lower than the middle grey level; and determining that the windows with balance figures greater than a predetermined threshold are not candidates for containing the bar code symbol.

Claim 17

A method of determining a location and orientation of a linear bar code symbol encoded in one direction and located in an image field, said image field being represented as a plurality of pixels having associated grey levels, and the pixels being organized into a plurality of windows, the method comprising the steps of: analyzing the grey levels of the pixels to determine a subset of said plurality of windows which contain part of the bar code symbol; and determining the direction in which the bar code symbol is encoded based on the subset of windows determined to contain part of the bar code symbol, wherein the step of analyzing the grey levels of the pixels includes the steps of: selecting from the plurality of windows a set of windows which are candidates for containing the bar code symbol; and examining the candidates to eliminate ones of the candidates which do not contain a part of the bar code symbol, and wherein the step of examining the candidates includes the steps of: forming the remaining candidates into clusters of contiguous candidates; and eliminating candidates formed in any cluster which is smaller than a predetermined size, wherein the step of selecting from the plurality of windows includes the steps of: determining a middle grey level for each of the windows as an average of the grey levels of a brightest pixel and a darkest pixel for each window; determining a balance figure for each of the windows from a magnitude of a difference between a number of pixels having a grey level higher than the middle grey level and a number of pixels having a grey level lower than the middle grey level; and determining that the windows with balance figures greater than a predetermined threshold are not candidates for containing the bar code symbol.

Claim 18

An apparatus for determining a location and orientation of a linear bar code symbol encoded in one direction and located in an image field, said image field being represented as a plurality of pixels having associated grey levels, and the pixels being organized into a plurality of windows, the apparatus comprising: means for analyzing the grey levels of the pixels to determine a subset of said plurality of windows which contain part of the bar code symbol; and means for determining the direction in which the bar code symbol is encoded based on the subset of windows determined to contain part of the bar code symbol, wherein the analyzing means comprises: means for selecting from the plurality of windows a set of windows comprising candidates for containing the bar code symbol; and means for examining the candidates to eliminate ones of the candidates which do not contain a part of the bar code symbol, and wherein the selecting means comprises: means for determining a middle grey level for each of the windows as an average of the grey levels of a brightest pixel and a darkest pixel for each window; means for determining a balance figure for each of the windows from a magnitude of a difference between a number of pixels having a grey level higher than the middle grey level and a number of pixels having a grey level lower than the middle grey level; and means for determining that the windows with balance figures greater than a predetermined threshold are not candidates for containing the bar code symbol.

Claim 19

An apparatus for determining a location and orientation of a linear bar code symbol encoded in one direction and located in an image field, said image field being represented as a plurality of pixels having associated grey levels, and the pixels being organized into a plurality of windows, the apparatus comprising: means for analyzing the grey levels of the pixels to determine a subset of said plurality of windows which contain part of the bar code symbol; and means for determining the direction in which the bar code symbol is encoded based on the subset of windows determined to contain part of the bar code symbol, wherein the analyzing means comprises: means for selecting from the plurality of windows a set of windows comprising candidates for containing the bar code symbol; and means for examining the candidates to eliminate ones of the candidates which do not contain a part of the bar code symbol, and wherein the selecting means comprises: means for determining a middle grey level for each of the windows as an average of the grey levels of a brightest pixel and a darkest pixel for each window; means for determining a balance figure for each of the windows from a magnitude of a difference between a number of pixels having a grey level higher than the middle grey level and a number of pixels having a grey level lower than the middle grey level; and means for determining that the windows with balance figures greater than a predetermined threshold are not candidates for containing the bar code symbol.