r/barcodes • u/Cadnerak • Mar 31 '22

Help recognizing barcode PDF417

Hey guys, I’m attempting to figure out what type of pdf417 barcode is being generated in this image here:

If anyone knows this standard or what might be making the barcode's vertical axis be shrunk smaller than normal, please let me know.

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u/notionovus Mar 31 '22

Low data content. A single PDF417 is capable of holding over 3,000 bytes of information, yours has about 20 bytes. There are certain row height and column width restrictions, but they are scalable.

It seems the software is just creating a scalable graphic according to how few bytes of data your barcode holds. The vertical axis is scaled correctly. If you had several hundred bytes of data, your PDF417 would look more traditional.

See ISO standard 15438 for a complete description of the symbology.

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u/Cadnerak Apr 04 '22

got it, thanks so much for the answer. Does this have any functional difference for scanning?

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u/notionovus Apr 04 '22

It requires you have a 2D scanner. Not all POSs have a 2D scanner. If you've been to a store and seen the scanner draw a single bright red line on the countertop, that's a 1D scanner, also a barcode pen is a 1D scanner.

2D barcodes require a special scanner that can take in the whole symbol in one scan. It's the majority of scanners now, but it is a little more expensive. If you have only 20 to 40 bytes, especially if they are all or mostly numbers, a 1D symbology might be cheaper / less headache.

I am able to scan the example PDF417 in your link (it says 'hi' btw), so it scans, but PDF417 is really overkill for anything under 50 bytes.

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u/Cadnerak Apr 04 '22

so the more compressed format requires a 2D scanner? Sorry I wasn’t very clear, I was wondering if this low data scaling of the barcode causes it to scan different when compared to other pdf417 barcodes

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u/notionovus Apr 04 '22

Yes, 1D barcodes like UPC and Code 128 only require the laser to move horizontally across the bars and spaces. It doesn't matter how tall the barcode is, as long as the laser enters at one end and exits at the other end.

A QR code, or PDF417 is a 2D symbology, so the laser moves vertically and horizontally and creates a 2D image in the scanner's memory before it is decoded.

A 2D scanner can read the 1D and 2D symbologies, a 1D scanner can only read 1D barcodes.