# Bar codes - NYU Computer Science Department

```Bar codes:
The little symbol that could
Nikki Candelore
Discrete Math: Summer ’08
Professor Langston
What is a bar code?
What we take for granted
Electronic
Cash
Register and
Scanner
Manufacturer
Centralized
Computer
EID
Store’s
Centralized
Computer
U.P.C: Younger than you’d think
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1930s – Harvard punch cards
1950s – Drexel blanks and bars
1970s catalysts
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1974, Wrigley’s gum in Troy Ohio
Rising inflation and impact of labor grocery
profitability
Deux ex machina – 1973 FDA regulation change
on labeling provides real impetus for change
Consumer outrage at prices being removed
1990s – take off
U.P.C: Younger than you’d think
Source: (Brown 4)
Universal Product Code: Main Features
Source: (http://www.barcodeart.com/science/science.html)
Universal Product Code: Main Features
Module Interpretation
Number Systems Chars
U.P.C. Digits
Source: (Brown 282, 287) and (http://electronics.howstuffworks.com/upc1.htm)
Universal Product Code: Built in Checks
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Inverted bars after middle guard bar
Splotches
Check Digit Calculation
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Sum odd digits (1, 3, 5..)
Multiply this by 3
Sum even digits (2, 4, 6..)
Add this to value in Step 2
Determine then number that added to the above
value would generate a multiple of 10
Universal Product Code: Built in Checks
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Check Digit Calculation: Example
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Sum odd digits (1, 3, 5..)
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Multiply this by 3
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96+11 = 107
Determine then number that added to the above value
would generate a multiple of 10
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3+3+2+0+3 = 11
Add this to value in Step 2
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32*3 = 96
Sum even digits (2, 4, 6..)
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6+9+8+0+0+9 = 32
107 + 3 = 110
Therefore 3 is our Check Digit
Other types of Bar Codes
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U.P.C. symbol
Code 39
Interleaved Two of Five
Source: (Gieco 30)
Code 2 of 5 and Interleaved 2 of 5
Source: (Baker 21)
Code 39
Source: (Baker 21)
The Future: 2D bar codes
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PDF417
2D bar codes build on
existing technology Stacked
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Stacks
Matrices
Check words
Fun applications
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p8t.ch website – 2D patches
URL
Source: (http://www.barcodeman.com/faq/2d.php)
Matrix
Identification
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