| 摘要 |
<p>A method and apparatus for detecting a bar code symbol in a continuous two-dimensional pixel image, such as an image generated by a video camera. After each new set of pixel image data is generated and stored in a circular buffer (1900), a set of pixel image data (1904) near the 'center' of the image data stored in the circular buffer is processed to detect bar code symbols. Processing image data for bar code symbols involves scanning along selected rows and columns of the image data. Scanning along a selected row or column involves identifying the locations of pixel-intensity-level transitions, storing the locations in a circular buffer, and testing the contents of the circular transition buffer for a wide bright region (corresponding to a bar code symbol quiet zone) adjacent to a dense sequence of transitions (corresponding to bars and spaces of a bar code symbol). Also, a method and apparatus for decoding a bar code symbol, wherein the width of each space (bar) is characterized according to the area under (over) the portion of the pixel intensity level 'curve' corresponding to that space (bar). The portion of the curve corresponding to a space (bar) is from the center of the previous bar (space) to the center of the following bar (space), where the centers are identified using a two-part scoring algorithm. The baseline level used to calculate the area under (over) the identified portion of the curve is based on the local dynamic range of pixel intensity levels and may be determined using a proportional integral filter.</p> |
