IronPDF: How to Reduce Output File Size with Base64 Image Headers and Footers for Large Multi-page PDFs

Overview

This article shows how to add an image-based header or footer to a PDF without inflating the output file size. After following it, you can keep a Base64 logo on every page while the file stays close to its original size.

Version Metadata

• Minimum Version: N/A

• Superseded-in Version: N/A

Steps

1. Split the header or footer into two HTML fragments. Put the image — and any text that never changes — in a static fragment. Put per-page content such as {page} in a dynamic fragment. Give both fragments the same table layout (same cell widths) so the dynamic text lands in the correct position over the static layer.
2. Add the static fragment first. Call AddHtmlHeadersAndFooters with only the static fragment. The Base64 image is rendered and embedded once.
3. Add the dynamic fragment in a second pass. Call AddHtmlHeadersAndFooters again with only the dynamic fragment. Because this pass contains no image, the per-page content stays small. If you render the static and dynamic parts together, the engine treats all of the HTML as dynamic and re-embeds the image on every page — which is what causes the file to grow.

   using IronPdf;
   
   var pdf = PdfDocument.FromFile("input.pdf");
   
   // Static layer: holds the Base64 image. The page-number cell is left empty.
   
   string staticFooter = @"
   <table style='width:100%; table-layout:fixed;'>
     <tr>
       <td style='width:20%;'>
         <img src='data:image/png;base64,iVBORw0KGg...' style='width:150px;' />
       </td>
       <td style='width:80%; text-align:right;'></td>
     </tr>
   </table>";
   
   // Dynamic layer: holds only {page}. Same layout, but no image.
   
   string dynamicFooter = $@"
   <table style='width:100%; table-layout:fixed;'>
     <tr>
       <td style='width:20%;'></td>
       <td style='width:80%; text-align:right; font-size:10px;'>Page  of {pdf.PageCount}</td>
     </tr>
   </table>";
   
   // Pass 1: add the static image footer (image embedded once).
   
   pdf.AddHtmlHeadersAndFooters(new ChromePdfRenderOptions
   {
       HtmlFooter = new HtmlHeaderFooter { HtmlFragment = staticFooter, MaxHeight = 40 }
   });
   
   // Pass 2: add the dynamic page-number footer (no image, stays small).
   
   pdf.AddHtmlHeadersAndFooters(new ChromePdfRenderOptions
   {
       HtmlFooter = new HtmlHeaderFooter { HtmlFragment = dynamicFooter, MaxHeight = 40 }
   });
   pdf.SaveAs("output.pdf");

    

    

4. (Optional) Use an external image file or an SVG instead of a Base64 string.
   If you don't need the image inlined as Base64, referencing an image file or using an SVG can reduce the output size further.

Notes and Limitations

• Both fragments must share the same table structure and cell widths, or the dynamic text (such as the page number) will not line up over the static layer.
• An external image file or an SVG can reduce file size further than a Base64 string.
• The same technique applies to headers: keep the image in the static pass and place any dynamic header text in the second pass.