Method and Apparatus for Locating and Decoding Machine-Readable Symbols

A device for recognizing two-width barcodes having N bars and N spaces, with each two-width barcode having M wide bars or spaces and N−M narrow bars or spaces, comprising:

• a unit for inputting an image of N bars and N spaces;
• and
• a processor that:
• sorts the N bars or spaces according to width in descending order from widest bar or space to narrowest bar or space;
• loops n, where n=1 to N−1, wherein a first class A of wide bars or spaces contains n elements Array [1] to Array [n], and a second class B of narrow bars or spaces contains N−n elements Array [n+1] to Array [N];
• calculates a mean value μA of class A and a mean value μB of class B, where
• μ
• A
• =
• ∑
• k
• =
• 1
• n
• 
• 
• Array
• 
• [
• k
• ]
• n
• ,
• 
• μ
• B
• =
• ∑
• k
• =
• n
• +
• 1
• N
• 
• 
• Array
• 
• [
• k
• ]
• N
• -
• n
• ;
• calculates a between-class difference D=μA−μB;
• records a value of n when D achieves a maximum value;
• and
• if n=M when D achieves the maximum value, then recognizes the N bars or spaces as a two-width barcode;
• otherwise, determines the N bars or spaces are not a two-width barcode.

One or more tangible, non-transitory computer-readable media embodying instructions executable by a computer to perform a method for recognizing two-width barcodes having N bars and N spaces, with each two-width barcode having M wide bars or spaces and N−M narrow bars or spaces, the method comprising:

• sorting the N bars or spaces according to width in descending order from widest bar or space to narrowest bar or space;
• looping n, where n=1 to N−1, wherein a first class A of wide bars or spaces contains n elements Array [1] to Array [n], and a second class B of narrow bars or spaces contains N−n elements Array [n+1] to Array [N];
• calculating a mean value μA of class A and a mean value μB of class B, where
• μ
• A
• =
• ∑
• k
• =
• 1
• n
• 
• 
• Array
• 
• [
• k
• ]
• n
• ,
• 
• μ
• B
• =
• ∑
• k
• =
• n
• +
• 1
• N
• 
• 
• Array
• 
• [
• k
• ]
• N
• -
• n
• ;
• calculating a between-class difference D=μA−μB;
• recording a value of n when D achieves a maximum value;
• and
• if n=M when D achieves the maximum value, then recognizing the N bars or spaces as a two-width barcode;
• otherwise, determining the N bars or spaces are not a two-width barcode.