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.