How To Redact PDF Documents In .NET Using The PDF Library

 //Create stream from an existing PDF document. 
FileStream docStream = new FileStream("Input.pdf", FileMode.Open, FileAccess.Read);
//Load the existing PDF document.
PdfLoadedDocument document = new PdfLoadedDocument(docStream);
//Get the first page from the document.
PdfLoadedPage page = document.Pages[0] as PdfLoadedPage;
//Create a redaction object.
PdfRedaction redaction = new PdfRedaction(new RectangleF(343, 147, 60, 17));
//Add a redaction object into the redaction collection of loaded page.
page.AddRedaction(redaction);
//Redact the contents from the PDF document.
document.Redact();
//Create file stream.
using (FileStream outputFileStream = new FileStream("Output.pdf", FileMode.Create, FileAccess.ReadWrite)) {
    //Save the PDF document to file stream.
    document.Save(outputFileStream);
}
//Close the document.
document.Close(true);

//Get stream from an existing PDF document.
FileStream docStream = new FileStream("Input.pdf", FileMode.Open, FileAccess.Read);
//Load the PDF document. 
PdfLoadedDocument document = new PdfLoadedDocument(docStream);
//Get the first page from the document.
PdfLoadedPage page = document.Pages[0] as PdfLoadedPage;
//Create a PDF redaction for the page.
PdfRedaction redaction = new PdfRedaction(new RectangleF(343, 147, 60, 17));
//Set fill color for the redaction bounds.
redaction.FillColor = Color.Red;
//Add a redaction object into the redaction collection of loaded page.
page.AddRedaction(redaction);
//Redact the contents from the PDF document.
document.Redact();
//Create file stream.
using (FileStream outputFileStream = new FileStream("Output1.pdf", FileMode.Create, FileAccess.ReadWrite)) {
    //Save the PDF document to file stream.
    document.Save(outputFileStream);
}
//Close the document.
document.Close(true);

//Get stream from an existing PDF document. 
FileStream docStream = new FileStream("Input.pdf", FileMode.Open, FileAccess.Read);
//Load the existing PDF document.
PdfLoadedDocument document = new PdfLoadedDocument(docStream);
//Get the first page from the document.
PdfLoadedPage page = document.Pages[0] as PdfLoadedPage;
//Create a redaction object.
PdfRedaction redaction = new PdfRedaction(new RectangleF(343, 147, 60, 17));
//Font for the overlay text.
PdfStandardFont font = new PdfStandardFont(PdfFontFamily.Courier, 10);
//Draw text on the redacted area.
redaction.Appearance.Graphics.DrawString("Redacted", font, PdfBrushes.Red, new PointF(5, 5));
//Add a redaction object into the redaction collection of loaded page.
page.AddRedaction(redaction);
//Redact the contents from the PDF document.
document.Redact();
//Create file stream.
using (FileStream outputFileStream = new FileStream("Output2.pdf", FileMode.Create, FileAccess.ReadWrite)) {
    //Save the PDF document to file stream.
    document.Save(outputFileStream);
}
//Close the document.
document.Close(true);

//Get stream from an existing PDF document. 
FileStream docStream = new FileStream("Input.pdf", FileMode.Open, FileAccess.Read);
//Load the existing PDF document.
PdfLoadedDocument document = new PdfLoadedDocument(docStream);
//Get the first page from the document.
PdfLoadedPage page = document.Pages[0] as PdfLoadedPage;
//Create a PDF redaction for the page.
PdfRedaction redaction = new PdfRedaction(new RectangleF(63, 57, 182, 157));
//Get stream from the image file.
FileStream imageStream = new FileStream("Image.jpg", FileMode.Open, FileAccess.Read);
//Load the image file. 
PdfImage image = new PdfBitmap(imageStream);
//Draw image on the redaction appearance. 
redaction.Appearance.Graphics.DrawImage(image, new RectangleF(0, 0, 182, 157));
//Add a redaction object into the redaction collection of loaded page.
page.AddRedaction(redaction);
//Redact the contents from the PDF document.
document.Redact();
//Create file stream.
using (FileStream outputFileStream = new FileStream("Output3.pdf", FileMode.Create, FileAccess.ReadWrite)) {
    //Save the PDF document to file stream.
    document.Save(outputFileStream);
}
//Close the document.
document.Close(true);