Question

I’m trying to transfer a byte array with QR code, so for testing, I decided to generate a random byte array, encode it as QR code, then decode it. I used ISO-8859-1 to convert byte array to string s.t it does not lose data while transmission:

For encoder side:

byte []buffer = new byte[11];
com.google.zxing.Writer writer = new QRCodeWriter();
Random randomGenerator = new Random();
    for(int i=0;i<=10;i++){
        buffer[i]=(byte) randomGenerator.nextInt(254);
    }
   // Log.i("time1","original: "+Arrays.toString(buffer));
    String decoded = null;
    try {
        decoded = new String(buffer, "ISO-8859-1");
    } catch (UnsupportedEncodingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    try {
        result=writer.encode(decoded, BarcodeFormat.QR_CODE, 500, 500);
    } catch (WriterException e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }

In this way I have converted byte array to QR code, it has no problem.
But for the receiver side:

LuminanceSource source = new PlanarYUVLuminanceSource(data,640,480,0,0,640,480,false);
bmtobedecoded = new BinaryBitmap(new HybridBinarizer(source));
Map<DecodeHintType,Object> mp=new HashMap<DecodeHintType, Object>();

mp.put(DecodeHintType.TRY_HARDER, true);
try {
    result= qrr.decode(bmtobedecoded,mp);
} catch (NotFoundException e) {
    Log.i("123","not found");
    e.printStackTrace();
} catch (ChecksumException e) {
    Log.i("123","checksum");
    e.printStackTrace();
} catch (FormatException e) {
    Log.i("123","format");
    e.printStackTrace();
}

I tried to decode the generated QR code, but it throws out NotFoundException.
Can someone help me with this issue?

Update 1: I confirmed that the decoder works perfectly with the normal QR, I also added DecodeHintType.try_harder but still no good.

Update 2: To clarify, below is what I did to convert between byte array and string:

Random randomGenerator = new Random();
for(int i=0;i<=10;i++){
    buffer[i]=(byte) randomGenerator.nextInt(254);
}
Log.i("time1","original: "+Arrays.toString(buffer));
String decoded = null;
try {
    decoded = new String(buffer, "ISO-8859-1");
} catch (UnsupportedEncodingException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}
Log.i("time1","encoded string:" + decoded);
BitMatrix result=null;
try {
    result=qw.encode(decoded, BarcodeFormat.QR_CODE, 500, 500);
} catch (WriterException e1) {
    // TODO Auto-generated catch block
    e1.printStackTrace();
}
iv.setImageBitmap(encodematrix(result));
byte[] encoded = null;
try {
    encoded = decoded.getBytes("ISO-8859-1");
} catch (UnsupportedEncodingException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
} 
Log.i("time1","result byte array:" + java.util.Arrays.toString(encoded));

If you run this, you can easily see that you can get exactly the same array in the end. I have no problem with this.

Update 3: I also tried encoding it using UTF-8, but it loses data, so it cannot be the used in encoder.

Update 4: Just added:

Map<DecodeHintType,Object> mp=new HashMap<DecodeHintType, Object>();
mp.put(DecodeHintType.CHARACTER_SET, "ISO-8859-1");

in the decoder, still throwing out exception.

Answer 1

Try PURE_BARCODE mode as a detection hint. Strangely, false positive detection of finder patterns is a much bigger problem when the image is just a pure synthetic image. The heuristics assume a photo, which doesn’t have these problems. In this alternate mode it can take advantage of knowing it’s a pure image and not a photo and be much faster and never get the detection wrong.