OpenXML - Is there a way to remove the washout feature of Microsoft Word watermark?

Question

When adding a watermark to the header of the word document, it automatically adds opacity to it. I want to remove that opacity and upon checking on the Microsoft Word itself, I found out that it can be removed by unchecking the Washout option. Can this be removed using OpenXML?

I followed the watermarking codes below:

using System.IO;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Wordprocessing;
using DocumentFormat.OpenXml;
using V = DocumentFormat.OpenXml.Vml;
using System.Diagnostics;

namespace WindowsFormsApplication3
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            using (WordprocessingDocument package = WordprocessingDocument.Open(@"C:\Users\*****\****.docx", true))
            {
                InsertCustomWatermark(package, @"C:\Users\*******\****.jpg");
            }
        }

        private void InsertCustomWatermark(WordprocessingDocument package, string p)
        {
            SetWaterMarkPicture(p);
            MainDocumentPart mainDocumentPart1 = package.MainDocumentPart;
            if (mainDocumentPart1 != null)
            {
                mainDocumentPart1.DeleteParts(mainDocumentPart1.HeaderParts);
                HeaderPart headPart1 = mainDocumentPart1.AddNewPart<HeaderPart>();
                GenerateHeaderPart1Content(headPart1);
                string rId = mainDocumentPart1.GetIdOfPart(headPart1);
                ImagePart image = headPart1.AddNewPart<ImagePart>("image/jpeg", "rId999");
                GenerateImagePart1Content(image);
                IEnumerable<SectionProperties> sectPrs = mainDocumentPart1.Document.Body.Elements<SectionProperties>();
                foreach (var sectPr in sectPrs)
                {
                    sectPr.RemoveAllChildren<HeaderReference>();
                    sectPr.PrependChild<HeaderReference>(new HeaderReference() { Id = rId });
                }
            }
            else
            {
                MessageBox.Show("alert");
            }
        }
        private void GenerateHeaderPart1Content(HeaderPart headerPart1)
        {
            Header header1 = new Header();
            Paragraph paragraph2 = new Paragraph();
            Run run1 = new Run();
            Picture picture1 = new Picture();
            V.Shape shape1 = new V.Shape() { Id = "WordPictureWatermark75517470", Style = "position:absolute;left:0;text-align:left;margin-left:0;margin-top:0;width:415.2pt;height:456.15pt;z-index:-251656192;mso-position-horizontal:center;mso-position-horizontal-relative:margin;mso-position-vertical:center;mso-position-vertical-relative:margin", OptionalString = "_x0000_s2051", AllowInCell = false, Type = "#_x0000_t75" };
            V.ImageData imageData1 = new V.ImageData() { Gain = "19661f", BlackLevel = "22938f", Title = "水印", RelationshipId = "rId999" };
            shape1.Append(imageData1);
            picture1.Append(shape1);
            run1.Append(picture1);
            paragraph2.Append(run1);
            header1.Append(paragraph2);
            headerPart1.Header = header1;
        }
        private void GenerateImagePart1Content(ImagePart imagePart1)
        {
            System.IO.Stream data = GetBinaryDataStream(imagePart1Data);
            imagePart1.FeedData(data);
            data.Close();
        }
        private string imagePart1Data = "";
        private System.IO.Stream GetBinaryDataStream(string base64String)
        {
            return new System.IO.MemoryStream(System.Convert.FromBase64String(base64String));
        }
        public void SetWaterMarkPicture(string file)
        {
            FileStream inFile;
            byte[] byteArray;
            try
            {
                inFile = new FileStream(file, FileMode.Open, FileAccess.Read);
                byteArray = new byte[inFile.Length];
                long byteRead = inFile.Read(byteArray, 0, (int)inFile.Length);
                inFile.Close();
                imagePart1Data = Convert.ToBase64String(byteArray, 0, byteArray.Length);
            }
            catch (Exception ex)
            {
                Debug.Print(ex.Message);
            }
        }
    }
}

Answer 1

We have found a solution for this. We compared the XML files of 2 .docx files, with and without watermark. The difference is that, the property Gain and BlackLevel from ImageData are now present from the .docx with watermark. We tried to remove the two said properties and it worked.