Method and device for identifying a two-dimensional barcode

A method of identifying a two-dimensional bar code in digital image data of the bar code, the bar code comprising first and second type elements arranged in an ordered grid and having an outline that comprises an L-shape clock line with transitions between the first and second type elements and an L-shape solid line without transitions between the first and second type elements, an intersection element at the corner of the L-shape clock line being of a predetermined type from the first and second type, wherein approximate corners in the digital image data determine a first and a second pair of opposite edge segments along the outline, the method comprising:

• scanning in the digital image data a first edge segment of the first pair and counting transitions between the first and second type elements along the first edge segment of the first pair;
• if no transitions were counted along the first edge segment of the first pair, then scanning in the digital image data the second edge segment of the first pair and counting transitions between the first and second type elements along the second edge segment of the first pair;
• determining which extremity of the edge segment of the first pair along which transitions were counted corresponds to the intersection element;
• scanning the edge segment of the second pair having the intersection element and counting transitions between the first and second type elements along the edge segment of the second pair having the intersection element;
• identifying the edge segment of the first pair and the edge segment of the second pair that intersect at the intersection element as the L-shape clock line of the bar code, and identifying the edge segment of the first pair and the edge segment of the second pair that not being part of the L-shape clock line as the L-shape solid line of the bar code.

An apparatus configured to identify a two-dimensional bar code in digital image data of the bar code, the bar code comprising first and second type elements arranged in an ordered grid and having an outline that comprises an L-shape clock line with transitions between the first and second type elements and an L-shape solid line without transitions between the first and second type elements, wherein approximate corners in the digital image data determine a first and a second pair of opposite edge segments along the outline, the apparatus comprising a processing unit being configured:

• to scan in the digital image data a first edge segment of the first pair and counting transitions between the first and second type elements along the first edge segment of the first pair;
• if no transitions were counted along the first edge segment of the first pair, then to scan in the digital image data the second edge segment of the first pair and counting transitions between the first and second type elements along the second edge segment of the first pair;
• to scan in the digital image data a first edge segment of the second pair and counting transitions between the first and second type elements along the first edge segment of the second pair;
• if no transitions were counted along the first edge segment of the second pair, then to scan in the digital image data the second edge segment of the second pair and counting transitions between the first and second type elements along the second edge segment of the second pair;
• to identify the edge segment of the first pair and the edge segment of the second pair along which transitions were counted as the L-shape clock line of the bar code, and to identify the edge segment of the first pair and the edge segment of the second pair along which no transitions were counted as the L-shape solid line of the bar code.

An apparatus configured to identify a two-dimensional bar code in digital image data of the bar code, the bar code comprising first and second type elements arranged in an ordered grid and having an outline that comprises an L-shape clock line with transitions between the first and second type elements and an L-shape solid line without transitions between the first and second type elements, an intersection element at the corner of the L-shape clock line being of a predetermined type from the first and second type, wherein approximate corners in the digital image data determine a first and a second pair of opposite edge segments along the outline, the apparatus comprising a processing unit being configured:

• to scan in the digital image data a first edge segment of the first pair and counting transitions between the first and second type elements along the first edge segment of the first pair;
• if no transitions were counted along the first edge segment of the first pair, then to scan in the digital image data the second edge segment of the first pair and counting transitions between the first and second type elements along the second edge segment of the first pair;
• to determine which extremity of the edge segment of the first pair along which transitions were counted corresponds to the intersection element;
• to scan the edge segment of the second pair having the intersection element and counting transitions between the first and second type elements along the edge segment of the second pair having the intersection element;
• to identify the edge segment of the first pair and the edge segment of the second pair that intersect at the intersection element as the L-shape clock line of the bar code, and to identify the edge segment of the first pair and the edge segment of the second pair that not being part of the L-shape clock line as the L-shape solid line of the bar code.