Method and apparatus for locating data regions in stored images of symbols

A method for computing an upper and lower bounding box of a Code One symbol having a recognition pattern, including a top bar adjacent the upper bounding box and a lower bar adjacent the lower bounding box, and four vertical reference bars, each having a foot portion end away from the recognition pattern and a root portion, the four vertical reference bars including first and second vertical reference bars where the root portion is contiguous with the top bar, and third and fourth vertical reference bars where the root portion is contiguous with the lower bar, said method comprising the steps of:

• locating a position of a first end point and a second end point of the top bar;
• determining the location of the root portion of the first and second vertical reference bars from the first and second end points, respectively;
• locating an inner corner of the foot of the first and second vertical reference bars from the root portion of the first and second vertical reference bars, respectively;
• crossing the foot of the first and second vertical reference bars to reach a top point of the first and second vertical reference bars;
• extrapolating from the top point of the first and second vertical reference bars in a first predetermined direction for a first predetermined distance to reach first and second corner points;
• projecting from the first and second end points in a second predetermined direction along the recognition pattern to third and fourth end points in line with the lower bar;
• determining the location of the root portion of the third and fourth vertical reference bars from the third and fourth end points, respectively;
• locating an inner corner of the foot of the third and fourth vertical reference bars from the root portion of the third and fourth vertical reference bars, respectively;
• crossing the foot of the third and fourth vertical reference bars to reach a bottom point of the third and fourth vertical reference bars;
• extrapolating from the bottom point of the third and fourth vertical reference bars in a third predetermined direction for a third predetermined distance to reach third and fourth corner points;
• defining the upper bounding box using the first and second end points as well as the first and second corner points;
• and
• defining the lower bounding box using the third and fourth end points as well as the third and fourth corner points.

An apparatus for decoding a machine-readable symbol representing encoded information, the symbol having a recognition pattern with an outermost bar and at least one vertical reference pattern extending approximately perpendicular from the recognition pattern, the apparatus comprising:

• a sensor that receives light reflected from the symbol and produces an output signal therefrom;
• a receiver that receives the output signal and produces a data signal indicative of the encoded information, the recognition pattern and the at least one vertical reference pattern;
• and
• a processor for decoding the encoded information encoded in the symbol, the processor being programmed to (a) locate a position of a first end point and a second end point of the outermost bar of the recognition pattern, (b) locate a position of an outermost point of each of the at least one vertical reference pattern, (c) determine a position of a first corner point and a second corner point for the symbol by extending at least one line from the outermost point a predetermined distance in a predetermined direction, wherein the first and second corner points differ from the first and second end points, (d) define a periphery of the symbol using the positions of the first end point, the second end point, the first corner point and the second corner point, and (e) decode the encoded information within the periphery of the symbol.

A method for computing a location of data regions in a stored image of a symbol, wherein the symbol includes a recognition pattern having an outermost bar and at least one vertical reference pattern extending approximately perpendicularly from the recognition pattern, the method comprising the steps of:

• identifying a position of first and second end points of the outermost bar of the recognition pattern;
• locating a position of an outermost point of the at least one vertical reference pattern, wherein the data regions in the stored image of the symbol extend on opposite sides of the at least one vertical reference pattern;
• identifying a position of first and second corner points for the stored image of the symbol, wherein the first and second corner points differ from the first and second end points;
• and
• identifying a periphery of the data regions in the stored image of the symbol based on the positions of the first and second end points and first and second corner points.

A method for computing a location of data regions in a stored image of an image of a symbol, wherein the symbol includes a recognition pattern having an outermost bar and at least one vertical reference pattern extending approximately perpendicularly from the recognition pattern, the method comprising the steps of:

• identifying a position of first and second end points of the outermost bar of the recognition pattern;
• locating a position of an outermost point of the at least one vertical reference pattern, wherein an image of the recognition pattern in the stored image fails to accurately define data regions in the stored image of the symbol;
• identifying a position of first and second corner points for the stored image of the symbol, wherein the first and second corner points differ from the first and second end points;
• and
• accurately defining a periphery of the data regions in the stored image of the symbol based on the positions of the first and second end points and first and second corner points.