VintaSoft Twain .NET SDK 15.4: Documentation for .NET developer
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How to acquire black-white images from eSCL scanner?
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If you want to acquire black-white images from eSCL scanner, you should set the scan color mode (using EsclDevice.ScanColorMode property) to the EsclScanColorMode.BlackAndWhite1 value.

Not all eSCL devices allows to acquire black-white images. Supported scan color modes can be obtained using EsclDevice.GetSupportedScanColorModes method.

Here is an example that demonstrates how to acquire black-white images from eSCL device:
/// <summary>
/// Acquires black-white images from eSCL device.
/// </summary>
public void AcquireBlackWhiteImageFromEsclDevice()
{
    // create eSCL device manager
    using (Vintasoft.EsclImageScanning.EsclDeviceManager deviceManager = new Vintasoft.EsclImageScanning.EsclDeviceManager())
    {
        // open eSCL device manager
        deviceManager.Open();

        // wait while the eSCL device manager searches for eSCL devices
        System.Threading.Thread.Sleep(deviceManager.DeviceSearchTimeout);
        // get count of eSCL devices
        int deviceCount = deviceManager.Devices.Count;
        if (deviceCount == 0)
        {
            System.Console.WriteLine("Devices are not found.");
            return;
        }

        // select the first eSCL device
        Vintasoft.EsclImageScanning.EsclDevice device = deviceManager.Devices[0];

        // open eSCL device
        device.Open();


        // get names of supported scan modes
        Vintasoft.EsclImageScanning.EsclScanColorMode[] supportedScanColorModes = device.GetSupportedScanColorModes();
        foreach (Vintasoft.EsclImageScanning.EsclScanColorMode supportedScanMode in supportedScanColorModes)
        {
            if (supportedScanMode == Vintasoft.EsclImageScanning.EsclScanColorMode.BlackAndWhite1)
            {
                // specify that black-white images must be acquired from eSCL device
                device.ScanColorMode = supportedScanMode;
                break;
            }
        }


        Vintasoft.EsclImageScanning.EsclAcquiredImage acquiredImage;
        do
        {
            try
            {
                // acquire image from eSCL device
                acquiredImage = device.AcquireImageSync();
                // if image is received
                if (acquiredImage != null)
                {
                    System.Console.WriteLine("Image is acquired.");
                }
                // if image is not received
                else
                {
                    System.Console.WriteLine("Scan is completed.");
                    break;
                }
            }
            catch (System.Exception ex)
            {
                System.Console.WriteLine(string.Format("Scan is failed: {0}", ex.Message));
                break;
            }
        }
        // while image is acquired
        while (acquiredImage != null);

        // close eSCL device
        device.Close();

        // close eSCL device manager
        deviceManager.Close();
    }

    System.Console.ReadLine();
}
''' <summary>
''' Acquires black-white images from eSCL device.
''' </summary>
Public Sub AcquireBlackWhiteImageFromEsclDevice()
    ' create eSCL device manager
    Using deviceManager As New Vintasoft.EsclImageScanning.EsclDeviceManager()
        ' open eSCL device manager
        deviceManager.Open()

        ' wait while the eSCL device manager searches for eSCL devices
        System.Threading.Thread.Sleep(deviceManager.DeviceSearchTimeout)
        ' get count of eSCL devices
        Dim deviceCount As Integer = deviceManager.Devices.Count
        If deviceCount = 0 Then
            System.Console.WriteLine("Devices are not found.")
            Return
        End If

        ' select the first eSCL device
        Dim device As Vintasoft.EsclImageScanning.EsclDevice = deviceManager.Devices(0)

        ' open eSCL device
        device.Open()


        ' get names of supported scan modes
        Dim supportedScanColorModes As Vintasoft.EsclImageScanning.EsclScanColorMode() = device.GetSupportedScanColorModes()
        For Each supportedScanMode As Vintasoft.EsclImageScanning.EsclScanColorMode In supportedScanColorModes
            If supportedScanMode = Vintasoft.EsclImageScanning.EsclScanColorMode.BlackAndWhite1 Then
                ' specify that black-white images must be acquired from eSCL device
                device.ScanColorMode = supportedScanMode
                Exit For
            End If
        Next


        Dim acquiredImage As Vintasoft.EsclImageScanning.EsclAcquiredImage
        Do
            Try
                ' acquire image from eSCL device
                acquiredImage = device.AcquireImageSync()
                ' if image is received
                If acquiredImage IsNot Nothing Then
                    System.Console.WriteLine("Image is acquired.")
                Else
                    ' if image is not received
                    System.Console.WriteLine("Scan is completed.")
                    Exit Try
                End If
            Catch ex As System.Exception
                System.Console.WriteLine(String.Format("Scan is failed: {0}", ex.Message))
                Exit Try
            End Try
            ' while image is acquired
        Loop While acquiredImage IsNot Nothing

        ' close eSCL device
        device.Close()

        ' close eSCL device manager
        deviceManager.Close()
    End Using

    System.Console.ReadLine()
End Sub