QR ECC level bug

Setting error correction level for QR code with function forBits has first bit reversed. So with numbers (0, 1, 2, 3) instead (L, M, Q, H) is (M, L, H, Q). Not big deal, but good to know.

BarcodeWriter writer = new BarcodeWriter();
writer.Options = new QrCodeEncodingOptions()
{
    Width = 100, 
    Height = 100, 
    ErrorCorrection = ErrorCorrectionLevel.forBits(codeQR.eccLevel)   //FIX: codeQR.eccLevel^1
};
writer.Format = BarcodeFormat.QR_CODE;
Bitmap QRcode = writer.Write(code);

[pzygielo]

@Martin12350 - note - per wikipedia: dark is 0 on even rows and 1 on odd rows

And if i got it correctly then L=00,

So L = [dark, dark]T is not 00 I guess.

[srowen]

No library will generate the bits 00 for L (or else it’s wrong). Source code might use constants 0-3 for L,M,H,Q internally, but that would be unrelated to its bit encoding.

To be clear, you will never be able to visually read off the information bits in a QR code. Everything is error-corrected, masked, or both. While EC level is encoded as 2 bits logically, there are no 2 modules on a QR code you can look at to read it as a human. In particular, EC+format info is 5 bits that’s actually encoded with BCH with an additional 15 bits of correction.