VintaSoftTwain Control v6.0
VintaSoftTwain Object / Device_ImageContrast Property
In This Topic
    Device_ImageContrast Property
    In This Topic
    Gets or sets the contrast of gray/palette/color images for current scan session.
    Property type
    Read-write property
    Visual Basic
    Public Property Device_ImageContrast As Single
    Return Type
    Call this property after Device_Open and before Device_AcquireImage.

    This property has effect only if you do not use User Interface (Device_ShowUI=False).

    You can get minimal and maximal value for this property by Device_ImageContrastMinValue and Device_ImageContrastMaxValue properties.

    Information about error that occurs during getting/setting property value can be get using the Error and ErrorString properties.
    This example shows how to set maximum contrast and acquire images from the device.
    Private VSTwain1 As New VintaSoftTwain()
    ''' <summary>
    ''' Scans images asynchronously.
    ''' </summary>
    Private Sub ScanImages()
        ' open the device manager
        If Not VSTwain1.DeviceManager_Open() Then
            Exit Sub
        End If
        ' open the device
        If Not VSTwain1.Device_Open Then
            Exit Sub
        End If
        ' scan images without UI
        VSTwain1.Device_ShowUI = False
        ' specify that maximal contrast must be used
        VSTwain1.Device_ImageContrast = VSTwain1.Device_ImageContrastMaxValue
        ' subscribe to the device events
        AddHandler VSTwain1.DeviceImageAcquired, AddressOf VSTwain1_ImageAcquired
        AddHandler VSTwain1.DeviceScanCompleted, AddressOf VSTwain1_ScanCompleted
        AddHandler VSTwain1.DeviceScanFailed, AddressOf VSTwain1_ScanFailed
        AddHandler VSTwain1.DeviceScanCanceled, AddressOf VSTwain1_ScanCanceled
        ' acquire images asynchronously
    End Sub
    Private Sub VSTwain1_ImageAcquired()
        ' get index of acquired image
        Dim imageIndex As Integer = VSTwain1.AcquiredImages_Count - 1
        ' save acquired image to TIFF file
        If Not VSTwain1.AcquiredImages_Save(imageIndex, "test.tif") Then
        End If
    End Sub
    Private Sub VSTwain1_ScanCompleted()
        Console.WriteLine("Scan is completed.")
    End Sub
    Private Sub VSTwain1_ScanFailed(errorString As String)
        Console.WriteLine(String.Format("Scan is failed: {0}.", errorString))
    End Sub
    Private Sub VSTwain1_ScanCanceled()
        Console.WriteLine("Scan is canceled.")
    End Sub
    See Also