C#/VB.NET: PDF에 이미지 워터마크 추가

PM> Install-Package Spire.PDF 

using Spire.Pdf;
    using System.Drawing;
    
    namespace AddImageWatermark
    {
        class Program
        {
            static void Main(string[] args)
            {
                //Create a PdfDocument object
                PdfDocument document = new PdfDocument();
    
                //Load a sample PDF document
                document.LoadFromFile(@"C:\Users\Administrator\Desktop\sample.pdf");
    
                //Load an image
                Image image = Image.FromFile(@"C:\Users\Administrator\Desktop\logo.png");
    
                //Get the image width and height
                int imgWidth = image.Width;
                int imgHeight = image.Height;
    
                //Loop through the pages
                for (int i = 0; i < document.Pages.Count; i++)
                {
                    //Get the page width and height
                    float pageWidth = document.Pages[i].ActualSize.Width;
                    float pageHeight = document.Pages[i].ActualSize.Height;
    
                    //Set the background opacity
                    document.Pages[i].BackgroudOpacity = 0.3f;
    
                    //Set the background image of current page
                    document.Pages[i].BackgroundImage = image;
    
                    //Position the background image at the center of the page
                    Rectangle rect = new Rectangle((int)(pageWidth - imgWidth) / 2, (int)(pageHeight - imgHeight) / 2, imgWidth, imgHeight);
                    document.Pages[i].BackgroundRegion = rect;
                }
    
                //Save the document to file
                document.SaveToFile("AddImageWatermark.pdf");
                document.Close();
            }
        }
    }

Imports Spire.Pdf
    Imports System.Drawing
    
    Namespace AddImageWatermark
        Class Program
            Shared  Sub Main(ByVal args() As String)
                'Create a PdfDocument object
                Dim document As PdfDocument =  New PdfDocument()
    
                'Load a sample PDF document
                document.LoadFromFile("C:\Users\Administrator\Desktop\sample.pdf")
    
                'Load an image
                Dim image As Image =  Image.FromFile("C:\Users\Administrator\Desktop\logo.png")
    
                'Get the image width and height
                Dim imgWidth As Integer =  image.Width
                Dim imgHeight As Integer =  image.Height
    
                'Loop through the pages
                Dim i As Integer
                For  i = 0 To  document.Pages.Count- 1  Step  i + 1
                    'Get the page width and height
                    Dim pageWidth As single =  document.Pages(i).ActualSize.Width
                    Dim pageHeight As single =  document.Pages(i).ActualSize.Height
    
                    'Set the background opacity
                    document.Pages(i).BackgroudOpacity = 0.3f
    
                    'Set the background image of current page
                    document.Pages(i).BackgroundImage = image
    
                    'Position the background image at the center of the page
                    Dim rect As Rectangle =  New Rectangle(CType((pageWidth - imgWidth) / 2,(Integer)(pageHeight - imgHeight) / 2,imgWidth,imgHeight, Integer))
                    document.Pages(i).BackgroundRegion = rect
                Next
    
                'Save the document to file
                document.SaveToFile("AddImageWatermark.pdf")
                document.Close()
            End Sub
        End Class
    End Namespace