I’ve written my own qr code generator. I followed both the ISO standard as well as a tutorial that I found online (http://www.thonky.com/qr-code-tutorial/). After following the tutorial as a test case (encoding “HELLO WORLD” in alphanumeric mode) I generated what appears to be a working qr code. It scans properly and everything looks happy.
However, upon closer investigation, I noticed that the qr codes generated by my library differ ever so slightly from the ones shown in the tutorial. I have verified that they both start with the same set of binary data to encode. The mask being used is also the same. Note that both my result and the one given in the tutorial both decode properly (thank you error correction!)
I am beginning to think that the results shown in the tutorial are wrong. I tried filling in some of the data by hand it seems to confirm my own result. Also, when I encoded the example given in the ISO standard (‘01234567’ encoded in numeric mode) I get the same result as is suggested. Only some of the qr code is different. Most of it looks identical.
So my question becomes: is there a tool that can give me error statistics on a qr code? Is there are set of standard test images I can compare against to confirm that my library works entirely correctly?
The easiest thing to do is to get some other platforms to see if they can decode them.
You can try ZXing – http://zxing.org/w/decode.jspx – which will give you the raw data encoded so you can see if you made any mistakes. It should also give you the error correction level etc.
If you just want to see if the text was encoded correctly, try:
http://www.onlinebarcodereader.com/
http://www.patrick-wied.at/static/qrgen/