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    Security Override Hacking Challenges Programming Challenges
    Barcode scanner - Programming challenge 13
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    09-16-2013 05:48 AM Barcode scanner - Programming challenge 13 | Edited by trietptm 09-16-2013 05:55 AM
    To solve challenge 13 on Barcode, I have used zbar (Python) to read the barcode's bars & spaces but it reads and produces no results.
    Could you give me some suggestions on how to read the spaces/bars in this barcode: http://i.imgur.com/OLdt7ji.png
    http://securityoverride.org/challenges/programming/13/index.php

    PS: I have tried other online barcode decoders but they all didn't find any barcode in the barcode image.
    I have read the link http://electronics.howstuffworks.com/gadgets/high-tech-gadgets/upc.htm/printable
    to understand UPC barcode, I could read the byte code by eyes and check it with check-digit manually but still don't know how to start on programming the scanner.
     
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    12-12-2013 01:34 AM RE: Barcode scanner - Programming challenge 13 | Edited by cindy313 12-25-2013 10:08 PM
    There's no real magic in a reader that can identify a series of narrow and wide white and black stripes. Every barcode reader does that.

    The firmware in the reader then converts the information according to the formats that are coded into it. If a valid conversion is found, the numeric/ASCII equivalent is returned.

    The trick is that a lot of formats look very similar. It's possible that a barcode can return one value when decoded in Format "A" and another when decoded in Format "B". It's important that the reader have an expectation (priority) of certain formats to prevent misinterpreting an unsupported barcode format.
    er.. you can foiiow the guide for reading barcodes!
    or http://www.buzzle.com/articles/how-does-a-barcode-scanner-function.html
    barcode
    barcode scanner
     
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    12-12-2013 02:54 AM RE: Barcode scanner - Programming challenge 13
    Programming 13 can be solved really simple if you parse the PNG image, extract first line of pixels, give values of 1 for pixels that are black and 0 to any other pixels. The rest is research. It's a UPC A and tones of info can be found online.
     
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    12-19-2013 05:55 AM RE: Barcode scanner - Programming challenge 13
    It's a UPC A and tones of info can be found online


    Indeed. After all you can find a library with an example code which is 80% identical to the code which solves the challange. So you just need to know how to google and the basic of coding. You also should not limit youself to one language. May it is easier to use the language with the better library support.


    BTW that's my last post for this challange. More is not needed to pass it Wink
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