background image not show in pdf

https://www.aspforums.net/Threads/203926/Display-watermark-image-in-PDF-using-iTextsharp-in-ASPNet-C-and-VBNet/  

 
OR

void makePDF()

{

Response.ContentType = "application/pdf";

Response.AddHeader("content-disposition", "attachment;filename=test.pdf");

Response.Cache.SetCacheability(HttpCacheability.NoCache);

string imageFilePath = Server.MapPath(".") + "/images/test.jpg";

iTextSharp.text.Image jpg = iTextSharp.text.Image.GetInstance(imageFilePath);

// Page site and margin left, right, top, bottom is defined

Document pdfDoc = new Document(PageSize.A4, 10f, 10f, 10f, 0f);

//Resize image depend upon your need

//For give the size to image

jpg.ScaleToFit(3000, 770);

//If you want to choose image as background then,

jpg.Alignment = iTextSharp.text.Image.UNDERLYING;

//If you want to give absolute/specified fix position to image.

jpg.SetAbsolutePosition(7, 69);

PdfWriter.GetInstance(pdfDoc, Response.OutputStream);

pdfDoc.Open();

pdfDoc.NewPage();

Paragraph paragraph = new Paragraph("this is the testing text for demonstrate the image is in background \n\n\n this is the testing text for demonstrate the image is in background");

pdfDoc.Add(jpg);

pdfDoc.Add(paragraph);

pdfDoc.Close();

Response.Write(pdfDoc);

Response.End();

}