How to read barcodes from color image with poor quality?

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There are 2 ways possible:

You should use the Automatic Recognition (see ReaderSettings.AutomaticRecognition)
You should use the iteration process of threshold detection

Here is C#/VB.NET code that demonstrates how to detect barcodes in a color image with difficult-to-locate threshold.

public static void TestScanWithIterationsCode128orDataMatrix(string fileName)
{
    // recognize one Code 128 or DataMatrix barcode from 300 to 600 threshold (20 iterations).
    ScanWithIterations(fileName, Vintasoft.Barcode.BarcodeType.Code128 | Vintasoft.Barcode.BarcodeType.DataMatrix, 1, 20, 300, 600);
}


public static void ScanWithIterations(
    string fileName,
    Vintasoft.Barcode.BarcodeType barcodes,
    int expectedBarcodes,
    int iterationCount,
    int minThreshold,
    int maxThreshold)
{
    // create a BarcodeReader object
    using (Vintasoft.Barcode.BarcodeReader reader = new Vintasoft.Barcode.BarcodeReader())
    {
        // set barcode reader settings
        reader.Settings.ScanBarcodeTypes = barcodes;
        reader.Settings.ExpectedBarcodes = expectedBarcodes;
        reader.Settings.ThresholdMode = Vintasoft.Barcode.ThresholdMode.Iterations;
        reader.Settings.ThresholdIterations = iterationCount;
        reader.Settings.ThresholdMin = minThreshold;
        reader.Settings.ThresholdMax = maxThreshold;

        // read barcodes
        Vintasoft.Barcode.IBarcodeInfo[] barcodesInfo = reader.ReadBarcodes(fileName);

        // if barcodes are not detected
        if (barcodesInfo.Length == 0)
        {
            System.Console.WriteLine("No barcodes found.");
        }
        // if barcodes are detected
        else
        {
            // get information about extracted barcodes
            for (int i = 0; i < barcodesInfo.Length; i++)
            {
                Vintasoft.Barcode.IBarcodeInfo inf = barcodesInfo[i];
                System.Console.WriteLine(string.Format("[{0}] {1} (Threshold: {2})", inf.BarcodeType,
                                                inf.Value, inf.Threshold));
            }
        }
    }
}

VB.NET

Public Shared Sub TestScanWithIterationsCode128orDataMatrix(fileName As String)
    ' recognize one Code 128 or DataMatrix barcode from 300 to 600 threshold (20 iterations).
    ScanWithIterations(fileName, Vintasoft.Barcode.BarcodeType.Code128 Or Vintasoft.Barcode.BarcodeType.DataMatrix, 1, 20, 300, 600)
End Sub


Public Shared Sub ScanWithIterations(fileName As String, barcodes As Vintasoft.Barcode.BarcodeType, expectedBarcodes As Integer, iterationCount As Integer, minThreshold As Integer, maxThreshold As Integer)
    ' create a BarcodeReader object
    Using reader As New Vintasoft.Barcode.BarcodeReader()
        ' set barcode reader settings
        reader.Settings.ScanBarcodeTypes = barcodes
        reader.Settings.ExpectedBarcodes = expectedBarcodes
        reader.Settings.ThresholdMode = Vintasoft.Barcode.ThresholdMode.Iterations
        reader.Settings.ThresholdIterations = iterationCount
        reader.Settings.ThresholdMin = minThreshold
        reader.Settings.ThresholdMax = maxThreshold

        ' read barcodes
        Dim barcodesInfo As Vintasoft.Barcode.IBarcodeInfo() = reader.ReadBarcodes(fileName)

        ' if barcodes are not detected
        If barcodesInfo.Length = 0 Then
            System.Console.WriteLine("No barcodes found.")
        Else
            ' if barcodes are detected
            ' get information about extracted barcodes
            For i As Integer = 0 To barcodesInfo.Length - 1
                Dim inf As Vintasoft.Barcode.IBarcodeInfo = barcodesInfo(i)
                System.Console.WriteLine(String.Format("[{0}] {1} (Threshold: {2})", inf.BarcodeType, inf.Value, inf.Threshold))
            Next
        End If
    End Using
End Sub

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