US 6,604,682 B2 · Method of and apparatus for reading a two-dimensional bar code symbol and data storage medium

Abstract

A two-dimensional bar code reading method and apparatus search the finder pattern in a scanned image of a two-dimensional bar code symbol, find orientation modules, find data modules, and convert the symbol to data characters as part of the decoding process for the scanned image of a MaxiCode symbol. In the data module search part of a MaxiCode symbol decoding process, position and shape information is calculated for data modules on an orientation axis, assuming an orientation axis passing the finder pattern center point, inside orientation module center point, and outside orientation module center point (step to S1801). Based on pixel data corresponding to the calculated location of the center point in each module, a bit pattern is generated where black data cells are 1 bits and white cells are 0 bits (S1802). The locations of MaxiCode symbol data modules in the area between orientation axes are then calculated (S1803). Pixel data corresponding to the calculated location of the center point of each data module is then converted to a bit pattern where black data cells are 1 bits and white data cells are 0 bits (S1804), and the data module search process then ends.

Claims65

Dependent claims

A method of reading a two-dimensional bar code symbol having orientation modules and a finder pattern with a center point, the method comprising a data module search step that calculates position and shape information for all modules constituting the bar code symbol by calculating an orientation axis passing through an orientation module and the finder pattern center point in a scanned image of the bar code symbol based on finder pattern position, orientation module position, and orientation module shape information in the scanned image, wherein the data module search step comprises the following steps:

(a) an orientation axis module position calculating step that calculates, based on finder pattern position information and orientation module position information and shape information, position and shape information for a plurality of modules constituting a module group on said orientation axis;
(b) an orientation axis data module bit pattern detecting step that detects a bit pattern of said plural data modules on the orientation axis calculated by the orientation axis module position calculating step;
(c) a between-orientation axis module position calculating step that calculates, based on the position and shape information of the plural modules of the module group on the orientation axis calculated by the orientation axis module position calculating step, position information for a plurality of modules constituting a module group between adjacent orientation axes;
and
(d) a between-orientation axis data module bit pattern detecting step that detects the bit pattern of the plural data modules present between the orientation axes calculated by the between-orientation axis module position calculating step.

2 more elements

A method of reading a two-dimensional bar code symbol having a finder pattern, the method comprising:

a finder pattern search step that searches a scanned image of the bar code symbol for a scan line where a detected pattern in a specific scanning direction matches a specified reference pattern, detecting the finder pattern in the scanned bar code symbol image based on plural searched scan lines, and obtaining finder pattern position and shape information, wherein the finder pattern search step comprises:
(a) scanning a scanned image of the bar code symbol in a first scanning direction;
(b) obtaining a first detection pattern by means of the first scanning step;
(c) comparing the first detection pattern obtained by step (b) with a previously stored specific reference pattern;
(d) defining said scan line as a first center line when step (c) determines the first detection pattern matches the specific reference pattern;
(e) scanning the finder pattern in a second scanning direction that is different from the first scanning direction;
(f) obtaining a second detection pattern by means of the second scanning step;
(g) comparing the second detection pattern with the previously stored specific reference pattern;
(h) defining said scan line as a second center line when step (g) determines the second detection pattern matches the specific reference pattern;
and
(i) setting the intersection of the first center line and the second center line as the center point of the finder pattern.

8 more elements

A method of reading a two-dimensional bar code symbol having a finder pattern, the method comprising:

a finder pattern search step that searches a scanned image of the bar code symbol for a scan line where a detected pattern in a specific scanning direction matches a specified reference pattern, detecting the finder pattern in the scanned bar code symbol image based on plural searched scan lines, and obtaining finder pattern position and shape information, wherein the finder pattern search step comprises:
(a) scanning a scanned image of a the bar code symbol in a first scanning direction;
(b) obtaining a first detection pattern by means of the first scanning step;
(c) comparing the first detection pattern obtained by step (b) with a previously stored specific reference pattern;
(d) setting said scan line as a first center line when step (c) determines the first detection pattern matches the specific reference pattern;
(e) setting the midpoint between the two intersections of the first center line and outside circumference member of the finder pattern as a first center point;
(f) repeating steps (b) to (e) after shifting parallel to the first center line to find plural first center points;
(g) calculating a distribution of said plural first center points to the second scanning direction, which is different from the first scanning direction;
(h) detecting a segment where the distribution to the second scanning direction is highest as a first line segment where the number of plural first center points in the second scanning direction is highest;
(i) scanning in a second scanning direction on a line where the number of plural center points in the second scanning direction is highest;
(j) obtaining a second detection pattern by means of the second scanning step;
(k) comparing the second detection pattern with the previously stored specific reference pattern;
(l) setting said scan line as a second center line when step (k) determines the second detection pattern matches the specific reference pattern;
and
(m) setting the midpoint between the two intersections of the second center line and outside circumference member of the finder pattern as a second center point;
(n) finding plural second center points by shifting parallel to the second center line direction and repeating steps (j) to (m);
(o) calculating a distribution of said plural second center points to the first scanning direction;
(p) detecting a segment where the distribution to the first scanning direction is highest as a second line segment where the number of plural second center points in the first scanning direction is highest;
and
(q) setting the finder pattern center point to the intersection of the first line segment and second line segment.

17 more elements

A method of reading a two-dimensional bar code symbol having a finder pattern, the method comprising:

a finder pattern search step that searches a scanned image of the bar code symbol for a scan line where a detected pattern in a specific scanning direction matches a specified reference pattern, detecting the finder pattern in the scanned bar code symbol image based on plural searched scan lines, and obtaining finder pattern position and shape information, wherein the finder pattern search step comprises:
(a) scanning a scanned image of the bar code symbol in a first scanning direction;
(b) obtaining a first detection pattern by means of the first scanning step;
(c) comparing the first detection pattern obtained by step (b) with a previously stored specific reference pattern;
(d) setting the midpoint between the two intersections of the scan line and outside circumference member of the finder pattern as a first center point when step (c) detects a match between the first detection pattern and the specific reference pattern;
(e) finding plural first center points by shifting parallel to the first scanning direction and repeating steps (b) to (d);
(f) scanning the finder pattern in a second scanning direction, which is different from the first scanning direction;
(g) obtaining a second detection pattern by means of the second scanning step;
(h) comparing the second detection pattern with the previously stored specific reference pattern;
(i) setting the midpoint between the two intersections of the scan line and outside circumference member of the finder pattern as a second center point when step (h) detects a match between the second detection pattern and the specific reference pattern;
(j) finding plural second center points by shifting parallel to the second scanning direction and repeating steps (g) to (i);
(k) setting the finder pattern center point to the intersection of a line connecting the plural first center points and a line connecting the plural second center points.

9 more elements

A method of reading a two-dimensional bar code symbol having a finder pattern, the method comprising:

a finder pattern search step that searches a scanned image of the bar code symbol for a scan line where a detected pattern in a specific scanning direction matches a specified reference pattern, detecting the finder pattern in the scanned bar code symbol image based on plural searched scan lines, and obtaining finder pattern position and shape information, wherein the finder pattern search step comprises:
(a) scanning a scanned image of the bar code symbol in a first scanning direction;
(b) obtaining a first detection pattern by means of the first scanning step;
(c) comparing the first detection pattern obtained by step (b) with a previously stored specific reference pattern;
(d) setting a first center line to the scan line from which the first detection pattern was obtained when step (c) detects a match between the first detection pattern and the specific reference pattern;
(e) setting the midpoint between the two intersections of the first center line and outside circumference member of the finder pattern as a first center point;
(f) scanning a second scanning direction different from the first scanning direction through the first center point;
(g) obtaining a second detection pattern by means of the second scanning step;
(h) comparing the second detection pattern with the previously stored specific reference pattern;
(i) setting a second center line to the scan line from which the second detection pattern was obtained when step (h) detects a match between the second detection pattern and the specific reference pattern;
(j) setting the midpoint between the two intersections of the second center line and outside circumference member of the finder pattern as a second center point;
(k) calculating two intersections of the first center line and inside circumference member of the finder pattern, and two intersections of the second center line and inside circumference member of the finder pattern, from the midpoint between two intersections of the second center line and outside circumference member of the finder pattern;
and
(l) setting a barycenter determined from the two intersections of the first center line and inside circumference member of the finder pattern, and two intersections of the second center line and inside circumference member of the finder pattern, as the finder pattern center point.

11 more elements

An apparatus for reading a two-dimensional bar code symbol, comprising:

a data module search unit that calculates position and shape information for all modules constituting the bar code symbol by calculating an orientation axis passing through an orientation module and finder pattern center point in a scanned image of the bar code symbol based on finder pattern position, orientation module position, and orientation module shape information in the scanned image, wherein the data module search unit comprises:
(a) an orientation axis module position calculating unit for calculating, based on finder pattern position information and orientation module position information and shape information, position and shape information for a plurality of modules constituting a module group on said orientation axis;
(b) an orientation axis data module bit pattern detecting unit for detecting a bit pattern of said plural data modules on the orientation axis calculated by the orientation axis module position calculating unit;
(c) a between-orientation axis module position calculating unit for calculating, based on the position and shape information of the plural modules of the module group on the orientation axis calculated by the orientation axis module position calculating unit, position information for a plurality of modules constituting a module group between adjacent orientation axes;
and
(d) a between-orientation axis data module bit pattern detecting unit for detecting the bit pattern of the plural data modules present between the orientation axes calculated by the between-orientation axis module position calculating unit.

3 more elements

A machine-readable data storage medium carrying a program for implementing steps of a method of reading a two-dimensional bar code symbol having orientation modules and a finder pattern with a center point, the method comprising:

a data module search step that calculates position and shape information for all modules constituting the bar code symbol by calculating an orientation axis passing through an orientation module and the finder pattern center point in a scanned image of the bar code symbol based on finder pattern position, orientation module position, and orientation module shape information in the scanned image, wherein the data module search step comprises the following steps:
(a) an orientation axis module position calculating step that calculates, based on finder pattern position information and orientation module position information and shape information, position and shape information for a plurality of modules constituting a module group on said orientation axis;
(b) an orientation axis data module bit pattern detecting step that detects a bit pattern of said plural data modules on the orientation axis calculated by the orientation axis module position calculating step;
(c) a between-orientation axis module position calculating step that calculates, based on the position and shape information of the plural modules of the module group on the orientation axis calculated by the orientation axis module position calculating step, position information for a plurality of modules constituting a module group between adjacent orientation axes;
and
(d) a between-orientation axis data module bit pattern detecting step that detects the bit pattern of the plural data modules present between the orientation axes calculated by the between-orientation axis module position calculating step.

3 more elements

A machine-readable data storage medium carrying a program for implementing steps of a method of reading a two-dimensional bar code symbol having a finder pattern, the method comprising:

a finder pattern search step that searches a scanned image of the bar code symbol for a scan line where a detected pattern in a specific scanning direction matches a specified reference pattern, detecting the finder pattern in the scanned bar code symbol image based on plural searched scan lines, and obtaining finder pattern position and shape information, wherein the finder pattern search step comprises:
(a) scanning a scanned image of a the bar code symbol in a first scanning direction;
(b) obtaining a first detection pattern by means of the first scanning step;
(c) comparing the first detection pattern obtained by step (b) with a previously stored specific reference pattern;
(d) setting said scan line as a first center line when step (c) determines the first detection pattern matches the specific reference pattern;
(e) setting the midpoint between the two intersections of the first center line and outside circumference member of the finder pattern as a first center point;
(f) repeating steps (b) to (e) after shifting parallel to the first center line to find plural first center points;
(g) calculating a distribution of said plural first center points to the second scanning direction, which is different from the first scanning direction;
(h) detecting a segment where the distribution to the second scanning direction is highest as a first line segment where the number of plural first center points in the second scanning direction is highest;
(i) scanning in a second scanning direction on a line where the number of plural center points in the second scanning direction is highest;
(j) obtaining a second detection pattern by means of the second scanning step;
(k) comparing the second detection pattern with the previously stored specific reference pattern;
(l) setting said scan line as a second center line when step (k) determines the second detection pattern matches the specific reference pattern;
and
(m) setting the midpoint between the two intersections of the second center line and outside circumference member of the finder pattern as a second center point;
(n) finding plural second center points by shifting parallel to the second center line direction and repeating steps (j) to (m);
(o) calculating a distribution of said plural second center points to the first scanning direction;
(p) detecting a segment where the distribution to the first scanning direction is highest as a second line segment where the number of plural second center points in the first scanning direction is highest;
and
(q) setting the finder pattern center point to the intersection of the first line segment and second line segment.

17 more elements

A machine-readable data storage medium carrying a program for implementing steps of a method of reading a two-dimensional bar code symbol having a finder pattern, the method comprising:

a finder pattern search step that searches a scanned image of the bar code symbol for a scan line where a detected pattern in a specific scanning direction matches a specified reference pattern, detecting the finder pattern in the scanned bar code symbol image based on plural searched scan lines, and obtaining finder pattern position and shape information, wherein the finder pattern search step comprises:
(a) scanning a scanned image of the bar code symbol in a first scanning direction;
(b) obtaining a first detection pattern by means of the first scanning step;
(c) comparing the first detection pattern obtained by step (b) with a previously stored specific reference pattern;
(d) setting the midpoint between the two intersections of the scan line and outside circumference member of the finder pattern as a first center point when step (c) detects a match between the first detection pattern and the specific reference pattern;
(e) finding plural first center points by shifting parallel to the first scanning direction and repeating steps (b) to (d);
(f) scanning the finder pattern in a second scanning direction, which is different from the first scanning direction;
(g) obtaining a second detection pattern by means of the second scanning step;
(h) comparing the second detection pattern with the previously stored specific reference pattern;
(i) setting the midpoint between the two intersections of the scan line and outside circumference member of the finder pattern as a second center point when step (h) detects a match between the second detection pattern and the specific reference pattern;
(j) finding plural second center points by shifting parallel to the second scanning direction and repeating steps (g) to (i);
(k) setting the finder pattern center point to the intersection of a line connecting the plural first center points and a line connecting the plural second center points.

9 more elements

A machine-readable data storage medium carrying a program for implementing steps of a method of reading a two-dimensional bar code symbol having a finder pattern, the method comprising:

a finder pattern search step that searches a scanned image of the bar code symbol for a scan line where a detected pattern in a specific scanning direction matches a specified reference pattern, detecting the finder pattern in the scanned bar code symbol image based on plural searched scan lines, and obtaining finder pattern position and shape information, wherein the finder pattern search step comprises:
(a) scanning a scanned image of the bar code symbol in a first scanning direction;
(b) obtaining a first detection pattern by means of the first scanning step;
(c) comparing the first detection pattern obtained by step (b) with a previously stored specific reference pattern;
(d) setting a first center line to the scan line from which the first detection pattern was obtained when step (c) detects a match between the first detection pattern and the specific reference pattern;
(e) setting the midpoint between the two intersections of the first center line and outside circumference member of the finder pattern as a first center point;
(f) scanning a second scanning direction different from the first scanning direction through the first center point;
(g) obtaining a second detection pattern by means of the second scanning step;
(h) comparing the second detection pattern with the previously stored specific reference pattern;
(i) setting a second center line to the scan line from which the second detection pattern was obtained when step (h) detects a match between the second detection pattern and the specific reference pattern;
(j) setting the midpoint between the two intersections of the second center line and outside circumference member of the finder pattern as a second center point;
(k) calculating two intersections of the first center line and inside circumference member of the finder pattern, and two intersections of the second center line and inside circumference member of the finder pattern, from the midpoint between two intersections of the second center line and outside circumference member of the finder pattern;
and
(l) setting a barycenter determined from the two intersections of the first center line and inside circumference member of the finder pattern, and two intersections of the second center line and inside circumference member of the finder pattern, as the finder pattern center point.

11 more elements

Dependencies are inferred from the claim text.

Method of and apparatus for reading a two-dimensional bar code symbol and data storage medium

Life of this patent

Method of and apparatus for reading a two-dimensional bar code symbol and data storage medium

Life of this patent

Abstract

Claims65