Abstract: A progressive-scan charge-coupled device (PSCCD) camera (2) may capture an entire frame of an image of an optically readable code. The camera generates a histogram or probability distribution function (PDF) of the images and uses the histogram or PDF to automatically adjust the contrast of the image. The camera also generates a cumulative distribution function (CDF) which is used to automatically adjust the illumination intensity including the brightness of the image and the duration over which the image is obtained. The captured analog video image is converted to a digital video image which may be output over the camera's bidirectional bus interface (14) to a component outside of the camera. Updated programs, parameters and other information may be sent in the opposite direction over the bus interface to the camera. The camera may be mounted at a fixed station or may be incorporated into a portable unit, and may be hand-held and/or battery operated.

Abstract: A bar code scanning system and method for scanning a bar code containing a key including successively scanning the bar code and providing, for each scan, a plurality of data elements forming a scan fragment for at least a portion of the bar code, identifying each fragment containing a portion of a reference key, detecting when there has been a match between a reference key and the identified key fragments, determining if a complete key has been constructed from the key fragments, calculating a displacement between the key fragments which constructed the complete key, and aligning data fragments of the bar code by placing each successive data fragment in alignment with the previous data fragment offset by the amount of the displacement.

Abstract: A frequency division multiplexed bar code scanner system includes a plurality of radiation sources for simultaneously providing a plurality of source beams, and a modulator circuit for modulating the intensity of each source beam at a different frequency. The source beams are combined and directed along a path to a bar code to be read; the return combined reflected light patterns are amplitude modulated by the bar code and are detected and the amplitude modulation of at least one of these patterns is detected to obtain a representation of the bar code read. The phase shift between the source beam and at least one of the reflected light patterns is used to determine the distance to the barcode bearing object. Distance information may be used to improve barcode reading performance.