将页眉和页脚图像添加到PDF:页眉图像没有'；t显示，页脚按比例放大

我正试图使用libary ITextSharp创建一个简单的.pdf。我正在制作一个.pdf，其中的标题&页脚中有图像，页眉边距为300px&页脚边距为664px。

我的问题：由于某种原因，我的代码没有插入页眉图像，并且由于某种原因页脚图像的大小被放大/放大。

你能告诉我我的代码出了什么问题吗标题图像应该扩展A4页面的整个宽度&高度为300像素。页脚图像应该扩展页面的整个宽度&高度为664px。这两个图像都不需要调整大小，它们已经是页面的整个宽度&正确的高度。

public class itsEventsHandler : PdfPageEventHelper
{
    PdfTemplate total;
    BaseFont helv;
    // I am following a tutorial & they said that if I want to create headers/footers when each page is created 
    // that I should override the OnEndPage() not the OnStartPage() is that correct?
    public override void OnEndPage(PdfWriter writer, Document document)
    {
        // Post: When each new page is created, add a header & footer image to the page. And set the top margin to 370px
        //       and the bottom margin to 664px.
        // Result: The function executes but the pdf's header image isn't visible & the footer looks resized(scaled up in size).
        //Footer Image 
        iTextSharp.text.Image imgfoot = iTextSharp.text.Image.GetInstance(resolvePath("~/images/pdf/bottomBorder.jpg"));
        //Header Image 
        iTextSharp.text.Image imghead = iTextSharp.text.Image.GetInstance(resolvePath("~/images/pdf/topBorder.jpg"));
        imgfoot.SetAbsolutePosition(0, 0);
        imghead.SetAbsolutePosition(0, 0);
        PdfContentByte cbhead = writer.DirectContent;
        PdfTemplate tp = cbhead.CreateTemplate(2480, 370); // units are in pixels but I'm not sure if thats the correct units
        tp.AddImage(imghead);
        PdfContentByte cbfoot = writer.DirectContent;
        PdfTemplate tpl = cbfoot.CreateTemplate(2480, 664); 
        tpl.AddImage(imgfoot);
        cbhead.AddTemplate(tp, 0, 0);
        cbfoot.AddTemplate(tpl, 0, 0);
        helv = BaseFont.CreateFont(BaseFont.HELVETICA, BaseFont.WINANSI, BaseFont.NOT_EMBEDDED);
        /*PdfContentByte cb = writer.DirectContent;
        cbfoot.SaveState();
        document.SetMargins(35, 35, 100, 82);
        cb.RestoreState();*/
        //document.NewPage(); 
        base.OnStartPage(writer, document);
    }
    public override void OnOpenDocument(PdfWriter writer, Document document)
    {
        total = writer.DirectContent.CreateTemplate(100, 100);
        total.BoundingBox = new iTextSharp.text.Rectangle(-20, -20, 100, 100);
        helv = BaseFont.CreateFont(BaseFont.HELVETICA, BaseFont.WINANSI, BaseFont.NOT_EMBEDDED);
    }
}
// My code to create the pdf
 // Create a Document object
var document = new Document(PageSize.A4, 50, 50, 370, 664);
var output = new MemoryStream();
var writer = PdfWriter.GetInstance(document, output);
writer.PageEvent = new itsEventsHandler();
// Open the Document for writing
document.Open();
// add some paragrahs
document.Close();

cbhead.AddTemplate(tp, 0, 715);
cbfoot.AddTemplate(tpl, 0, 0);