Reversing Convolution Distortion in a Laser Bar Code Scanner

This paper addresses the convolution distortion in a flying laser bar code scanner and its impact on bar code decoding. The convolution distortion is characterized in terms of beam width-to-narrow element ratio and modulation transfer function. The limits of decoding of a regular scanner are established. Then an edge detection method, which reverses convolution distortion, is presented. This method allows for improving the reading range of a scanner, eliminates mis-reads, and allows for optimizing the scanner optics. The performance of the proposed algorithm is evaluated and compared to the performance of a regular scanner.