For HTML2PDF and XML2PDF solution check our PDFDoc Scout ActiveX library instead

using System;
using System.Collections.Generic;
using System.Text;
using Bytescout.PDF;
using System.Diagnostics;

namespace HelloWorld
{
class Program
{
static void Main(string[] args)
{
// Create main PDF Doc Engine
PDFDocEngine engine = new PDFDocEngine("", "");

// Add new document
Document document = engine.AddDocument("Document.pdf");

// Add image to PDF
uint resIndex = document.AddImage("mylogo.png", 0, ImageCompressionType.JPEG);

for (uint i = 0; i < 4; i++)
{
// Append new page to the document
Page page = document.GetPage(i);

// Create new drawing
Drawing drawing = page.AddDrawing();

// Save the current graphics state on the graphics state stack
drawing.StateStore();

// Create new graphic state
DrawingState drawingState = new DrawingState(document);

// Set fill alpha blending to 30%
drawingState.AlphaFill = 0.3f;
// Set lines alpha blending to 100%
drawingState.AlphaStroke = 1.0f;
// Set graphic state as current
drawing.SetGState(drawingState);

// Place image
drawing.PlaceImage(resIndex, 0, 0, drawing.Width, drawing.Height, 0);

// Restore previous graphics state
drawing.StateRestore();

// Closing drawing on the page
drawing.Close();
}
// Save document
document.Save("Result.pdf");

// open generated PDF document in default PDF viewer installed in Windows
Process.Start("Result.pdf");
}
}
}

Download example source code: bytescoutpdf_watermarking_pdf_documents_with_logo.zip (80 KB)

For HTML2PDF and XML2PDF solution check our PDFDoc Scout ActiveX library instead