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Locating 2-D bar codes

  • US 5,304,787 A
  • Filed: 06/01/1993
  • Issued: 04/19/1994
  • Est. Priority Date: 06/01/1993
  • Status: Expired due to Term
First Claim
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1. A method for locating and determining the bounds of a two-dimensional bar code image including identifiable start and stop patterns, comprising the steps of:

  • (a) providing a stored image representing a scanned image area which may include said two-dimensional bar code image;

    (b) sampling said stored image along spaced parallel scan lines in a first direction across a potential bar code image location included in said image area, to provide scan line samplings;

    (c) repeating said step (b) sampling in at least one additional direction having an angular separation from said first direction, to provide additional scan line samplings;

    (d) analyzing scan line samplings provided in steps (b) and (c) to identify bar code start and stop pattern traversals where said samplings cross said patterns;

    (e) correlating said bar code start and stop patterns as representative of a common bar code image (i) when two start patterns, or two stop patterns, are identified in scan line samplings taken along parallel scan lines having not more than a predetermined lateral spacing, and (ii) when a start pattern and a stop pattern are identified in the same scan line sampling with said start and stop patterns having not more than a predetermined separation, to identify correlated start and stop pattern traversals representative of said bar code image;

    (f) utilizing said correlated start and stop pattern traversals representative of said bar code image to identify a nominally rectangular area bounding said bar code image; and

    (g) making available data representative of the location of said nominally rectangular area within said scanned image area.

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