''' <summary>
''' Corrects perspective distortion of document image.
''' </summary>
''' <param name="sourceFile">Source image file.</param>
''' <param name="resultFile">Result image file.</param>
''' <param name="documentImagePoints">An array of four points, which define the corner points of document image.
''' Points should be set in the following order: 0 - top-left, 1 - top-right,
''' 2 - bottom-left, 3 - bottom-right.</param>
Public Sub ApplyQuadrilateralUnwarp(sourceFile As String, resultFile As String, documentImagePoints As System.Drawing.PointF())
    Using image As New Vintasoft.Imaging.VintasoftImage(sourceFile)
        ' create the perspective correction command
        Dim command As New Vintasoft.Imaging.ImageProcessing.Transforms.QuadrilateralWarpCommand()

        ' specify that command must use invert transform (command must work as unwarp command)
        command.IsInverseTransform = True

        ' set the corner points of document image
        command.DestinationPoints = documentImagePoints

        ' apply perspective correction to a document image
        command.ExecuteInPlace(image)

        ' save the result image to a file
        image.Save(resultFile)
    End Using
End Sub

/// <summary>
/// Corrects perspective distortion of document image.
/// </summary>
/// <param name="sourceFile">Source image file.</param>
/// <param name="resultFile">Result image file.</param>
/// <param name="documentImagePoints">An array of four points, which define the corner points of document image.
/// Points should be set in the following order: 0 - top-left, 1 - top-right,
/// 2 - bottom-left, 3 - bottom-right.</param>
public void ApplyQuadrilateralUnwarp(string sourceFile, string resultFile, System.Drawing.PointF[] documentImagePoints)
{
    using (Vintasoft.Imaging.VintasoftImage image =
        new Vintasoft.Imaging.VintasoftImage(sourceFile))
    {
        // create the perspective correction command
        Vintasoft.Imaging.ImageProcessing.Transforms.QuadrilateralWarpCommand command =
            new Vintasoft.Imaging.ImageProcessing.Transforms.QuadrilateralWarpCommand();

        // specify that command must use invert transform (command must work as unwarp command)
        command.IsInverseTransform = true;

        // set the corner points of document image
        command.DestinationPoints = documentImagePoints;

        // apply perspective correction to a document image
        command.ExecuteInPlace(image);

        // save the result image to a file
        image.Save(resultFile);
    }
}