Abstract: A method of identifying a two-dimensional bar code in digital image data of the bar code having first and second type elements arranged in an ordered grid and an outline that includes an L-shape solid line without transitions between the first and second type elements. The method includes calculating a gradient field from the digital image data, specifying a gradient of the pixel value in the digital image data; calculating gradient magnitude data from the gradient field; performing a thresholding operation on the calculated gradient magnitude data and obtaining edge segment image data; detecting linear segments in the edge segment image data; identifying pairs of the detected linear segments; and sampling partial digital image data and detecting a presence of the first and second type elements in partial digital image data.

Abstract: 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, 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; scanning in the d

Abstract: 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, 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; scanning in the d

Abstract: 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 solid line without transitions between the first and second type elements, the method comprising calculating a gradient field from the digital image data, the gradient field specifying a gradient of the pixel value in the digital image data; calculating gradient magnitude data from the gradient field; performing a thresholding operation on the calculated gradient magnitude data and obtaining edge segment image data; detecting linear segments in the edge segment image data; identifying pairs of the detected linear segments based on an angular criterion between two of the detected linear segments and based on a distance criterion considering a distance between one extremity of each of the two linear segments; and sampling partial digital image data corresponding to a rectangle area in the digit