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BARCODES : A Mystery Unraveled

Good Morning readers ! Let's see what today we have here in our menu. Pretty familiar term right ? Shopping freaks may have seen it millions of time and so are the ones who like to try every new novel in store. So what's so special about these random straight lines ?

When you go to pay for something in a store, the assistant scans the bar code. As the laser scans the black and white stripes, it picks up a pattern. Instantly, the store’s computer knows what you’re buying and tells the till how much you’ve got to pay. So what’s the bar code saying?

Looks like it wants to say something. Let's find out what it is!

Beginning of the code shows two bars and a space at the beginning tell the computer that the code has begun.



This is the 1st part of the code which indicates country and/or manufacturer the product has come from.








Next up is again the two bars and three spaces in the middle separate the two halves of the bar code.



The second part of the
code identifies exactly
what the product is. Note here the last digit '1' is a
“checksum”—a digit
worked out using the
eleven previous numbers.


The last two bars and one space tell the computer that the code has finished.

Now isn't that something ? We have decoded the layout of a barcode but still we have no idea what these random bars show. In the next section we are going to find out how width of each stripe along with the number associated with it is calculated.

What the stripes mean
The stripes are a code that represents numbers in the form of bars and spaces. Each number is shown by a set of two bars and two spaces. The bars and spaces can be one, two, three, or four units wide. The number the scanner reads depends on the combination of different widths in each set of four bars and spaces.




How the numbers add up
Below are the numbers 0 to 9 in their bar code form. For each number there are two versions—the first one is used in the first half of the bar code and the second version is used in the second half. The second version is the same as the first,but substitutes bars for spaces, and vice versa. Representing the numbers in the two halves in a different way like this means that the bar code can be scanned in any direction and the computer can still figure out which bit of information is which.




For ex. check out the pattern of stripes and corresponding numbers for '0' - In the first half of the code, there are 3 units of blank spaces, 2 units of black stripe, 1 unit of blank space and 1 unit of black stripe respectively. Hence the sequence 3-2-1-1 


So that's a barcode is written !
Grab the latest magazine you purchased from store and start deciphering it.
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