trouble decoding code 39 on some images

[Andrew Z]

All of my barcodes are Code 39. They are generated and printed in a similar way, but sometimes the software doesn't detect any barcode.

I am test using the online scanner
http://zxing.org/w/decode.jspx

Here is a sample file that was scanned at 200dpi. It was never compressed with a lossy compression like JPG.

http://katana.oooninja.com/tmp/barcode0009b.png

Thank you in advance

Andrew

[Bas Vijfwinkel]

Most of the barcode decoders can't decode it for some reason.
This one was able to decode it :
http://www.datasymbol.com/barcode-recognition-sdk/barcode-reader/online-barcode-decoder.html.
It seems to be the resolution of the image / barcode that is not sufficient for
proper detection of the barcode.
Some of the black line are just a grey blur.
I presume the decoder from Datasymbol has a much more precise detector or maybe uses a more efficient way to detect the black-white changes and relate them to the correct encoding.
Could you maybe just try to take a picture of the barcode itself and feed that to the decoder? If that solves the problem then the resolution of the entire image might be what is causing the problem.

[Andrew Z]

I made a new scan at a higher resolution (300DPI). Now zxing (online app) does not decode the barcode from the whole image, but zbarimg.exe works. After I manually crop to just the barcode and text beneath it, zxing decodes it.

Is there a way to avoid manual cropping? I'm looking for a reliable, automated system.

Best regards
Andrew

[Sean Owen]

You should use TRY_HARDER mode and try different binarizers. It will always be beneficial to crop away the regions that definitely do not have a barcode.

[Andrew Z]

On Friday, July 11, 2014 2:07:20 PM UTC-6, Sean Owen wrote:
> You should use TRY_HARDER mode and try different binarizers. It will always be beneficial to crop away the regions that definitely do not have a barcode.

Thank you, Sean.

I don't see these options on the web interface. Is there a demo to try these options online or on Windows without building zxing from source?

Andrew

[Sean Owen]

These are options you use in the Java source code, I mean. No it's not an option on the web. There is a "CommandLineRunner" with these options, although you compile the java source (or grab the .jar from Maven) to be able to run it.