QRCode Decode from PDF using Thoughtworks QRCode

Using Thoughtworks and spirepdf trying to decode QR code

Check the code below

private static void GetImages(string sourcePdf, string outputPath)
{
PdfDocument doc = new PdfDocument();
doc.LoadFromFile(sourcePdf);
outputPath = System.IO.Path.Combine(outputPath, String.Format(@"{0}.jpg", 0));
for (int i = 0; i < doc.Pages.Count; i++)
{
string QRCodeString = "";
PdfPageBase page = doc.Pages[i];
System.IO.Stream[] images = page.ExtractImages();
foreach (System.IO.Stream image in images)
{
QRCodeString = GetQRCodeString(Bitmap.FromStream(image), outputPath);
if (QRCodeString == "")
{
continue;
//QRCodeString == "Not supported in Spire.Barcode Evaluation version. " ||
}
else
{
QRCodeDecoder decoder = new QRCodeDecoder();
String decodedString = decoder.decode(new QRCodeBitmapImage(new System.Drawing.Bitmap(image)), System.Text.Encoding.UTF8);
Console.WriteLine(decodedString);
}
}
Console.WriteLine(QRCodeString);
}
}
private static string GetQRCodeString(System.Drawing.Image img, string outPutPath)
{
img.Save(outPutPath, System.Drawing.Imaging.ImageFormat.Jpeg);
string scaningResult = Spire.Barcode.BarcodeScanner.ScanOne(outPutPath);
System.IO.File.Delete(outPutPath);
return scaningResult;
}

It is working for those pdf having Bar code at the top right corner. And showing for other positions

Error: ThoughtWorks.QRCode.ExceptionHandler.DecodingFailedException: 'Give up decoding'

Please help

Hello,

It may be the case the image you're working with has artifacts present interfering with the recognition process, or only examining a region of the document is a limitation of the library you're working with. Does the QR code contain the same data on each of the images? If not, the issue may be unrelated to its position on the page but this can't be determined without examining the images directly.

If you're not averse to using a commercial product (note I work for this vendor), the LEADTOOLS SDK has a QR code recognition module and an array of preprocessing techniques which can improve the recognition accuracy. Here's how you can do this:

RasterCodecs codecs = new RasterCodecs();
RasterImage image = codecs.Load(Path.Combine(folder, file));
BarcodeReader reader = new BarcodeEngine().Reader;
BarcodeData[] data = reader.ReadBarcodes(image, LeadRect.Empty, 0, new BarcodeSymbology[] { BarcodeSymbology.QR});
for (int i = 0; i < data.Length; i++)
{
Console.WriteLine(data[i].Value);
}

https://www.leadtools.com/downloads

1 Reply

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Ben Thompson5y ago
Hello,
It may be the case the image you're working with has artifacts present interfering with the recognition process, or only examining a region of the document is a limitation of the library you're working with. Does the QR code contain the same data on each of the images? If not, the issue may be unrelated to its position on the page but this can't be determined without examining the images directly.
If you're not averse to using a commercial product (note I work for this vendor), the LEADTOOLS SDK has a QR code recognition module and an array of preprocessing techniques which can improve the recognition accuracy. Here's how you can do this:
RasterCodecs codecs = new RasterCodecs();
RasterImage image = codecs.Load(Path.Combine(folder, file));

BarcodeReader reader = new BarcodeEngine().Reader;

BarcodeData[] data = reader.ReadBarcodes(image, LeadRect.Empty, 0, new BarcodeSymbology[] { BarcodeSymbology.QR});

for (int i = 0; i < data.Length; i++)
{
Console.WriteLine(data[i].Value);
}
https://www.leadtools.com/downloads