Abstract: Hand-held devices are provided for both scanning and decoding coded images such as two-dimensional bar codes. A linear scanning array of image sensing elements in the scanner/decoder provides image data with pixel-to-pixel synchronism, but lacking scan-to-scan synchronism as the scanning array is moved transversely across the bar code image. No tracking ball or roller is included to provide data enabling scan-to-scan synchronism. Redundant scan cancellation is employed to delete redundant image data from the stored image, with the adequate representation of coded information taking precedence over storage of a high resolution image. The stored image is sampled to correlate bar code edge pattern elements in order to identify the bounds and orientation of scanned bar code images. The redundancy-reduced stored bar code image is decoded within the hand-held unit, with use of data on bar code bounds and orientation, to provide decoded information for further use.

Abstract: After a two-dimensional bar code is scanned to provide a stored image, the location (i.e., bounds, including orientation) of the bar code image within the scanned area image must be determined to enable decoding. Methods for locating the bar code image include the steps of sampling the stored image, identifying sampling traversals of bar code start and stop patterns, and correlating the identified start and stop pattern traversals to a common bar code image. The correlating data is then used to identify a nominally rectangular area bounding the bar code image. A bounding box may be identified as the smallest area capable of encompassing all of the start and stop pattern traversals related to a common bar code image. Output location data may specify the coordinates of the four corners of a bounding box for use in subsequent decoding. Related systems are described.