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our company is looking to publish a desk calendar with a QR code. I know how to generate QR's, but do I need it to be a certain "resolution" or whatever if it's going to go through a professional printer? Thx!

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closed as off topic by Indrek, Ƭᴇcʜιᴇ007, Renan, Kyle, Diogo Sep 22 '12 at 1:26

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Like anything, a printed QR code needs to have a certain resolution. For good results it should have at least 300 dpi to look sharp.

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Thanks Martin! I used a free service to generate my QR, are there certain services that allow you to generate at a higher res that youre aware of? –  ewitkows Sep 21 '12 at 14:19
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As long as it's scaled at a whole multiple (2x, 4x, not 1.43x), upscaling a QR Code isn't an issue. –  afrazier Sep 21 '12 at 14:24
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You won't need a different service. For example, if you generate a PNG with, say 300px by 300px you can change the resolution to 300 dpi. The result will be printed 1 inch by 1 inch. That could already be enough for your purpose. Or, as afrazier spotted, 150 dpi would be enough, so you will get 2 inches by 2 inches. And so on. –  Martin Sep 21 '12 at 14:27
    
Super, thanks for the help! –  ewitkows Sep 21 '12 at 14:29
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What you don't want though is pixel rounding to reduce readability. Given, QR codes can be fairly damage resistant (depending on how they were generated), but that's an easy thing to do right to increase readability, so you have more room for error when it really counts. I've seen things like pixel rounding, poor scaling, and halftone patterns cause major problems with various barcode types. Just because a QR code can be readable with the pixels rounded off doesn't make it a good idea (and yes, I've seen that too). –  afrazier Sep 21 '12 at 16:22

There are actually different error correction levels defined in the QR code algorithm. The idea is to include additional data in the QR code in case it's hard to read or partially damaged.

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Image source

The resolution is less important, as long as the code is readable. QR code were designed exactly for this purpose. They should be easily readable to provide a Quick Response.

Also, make sure to pick a version and size that is appropriate for your data. Using a version 40 code to hold 40 characters makes no sense. Pick the lowest possible values that are sufficient to hold your data. But keep in mind that the error correction data has to fit into it as well.

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Good point on the version and size Oliver, fortunately I dont think that will be too much of an issue.. we'll be publishing a basic URL at this time, so I dont think we'll need a very large version. Thx! –  ewitkows Sep 21 '12 at 16:42

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