Replace Images with Higher Quality Images

protected void convertToPdfButton_Click(object sender, EventArgs e)
{
    // Create a HTML to PDF converter object with default settings
    HtmlToPdfConverter htmlToPdfConverter = new HtmlToPdfConverter();

    // Set license key received after purchase to use the converter in licensed mode
    // Leave it not set to use the converter in demo mode
    htmlToPdfConverter.LicenseKey = "4W9+bn19bn5ue2B+bn1/YH98YHd3d3c=";

    // Set an adddional delay in seconds to wait for JavaScript or AJAX calls after page load completed
    // Set this property to 0 if you don't need to wait for such asynchcronous operations to finish
    htmlToPdfConverter.ConversionDelay = 2;

    // Select all images from HTML page
    htmlToPdfConverter.HtmlElementsMappingOptions.HtmlElementSelectors = new string[] { "img" };

    // Exclude the original images from rendering becuase they will be replaced by an image from local file system
    htmlToPdfConverter.HiddenHtmlElementsSelectors = new string[] { "img" };

    Document pdfDocument = null;
    try
    {
        // Convert a HTML string with images to replace to a PDF document object
        pdfDocument = htmlToPdfConverter.ConvertUrlToPdfDocumentObject(urlTextBox.Text);

        // Replace the images selected in HTML using special attributes with images from local file system
        foreach (HtmlElementMapping imageElementInfo in htmlToPdfConverter.HtmlElementsMappingOptions.HtmlElementsMappingResult)
        {
            PdfPage imagePdfPage = imageElementInfo.PdfRectangles[0].PdfPage;
            RectangleF imageRectangle = imageElementInfo.PdfRectangles[0].Rectangle;

            ImageElement newImageElement = new ImageElement(imageRectangle.X, imageRectangle.Y, imageRectangle.Width, imageRectangle.Height,
                            Server.MapPath("~/DemoAppFiles/Input/Images/box.jpg"));
            newImageElement.EnlargeEnabled = true;
            imagePdfPage.AddElement(newImageElement);
        }

        // Save the PDF document in a memory buffer
        byte[] outPdfBuffer = pdfDocument.Save();

        // Send the PDF as response to browser

        // Set response content type
        Response.AddHeader("Content-Type", "application/pdf");

        // Instruct the browser to open the PDF file as an attachment or inline
        Response.AddHeader("Content-Disposition", String.Format("attachment; filename=Replace_with_Higher_Quality_Images.pdf; size={0}", outPdfBuffer.Length.ToString()));

        // Write the PDF document buffer to HTTP response
        Response.BinaryWrite(outPdfBuffer);

        // End the HTTP response and stop the current page processing
        Response.End();
    }
    finally
    {
        // Close the PDF document
        if (pdfDocument != null)
            pdfDocument.Close();
    }
}

Protected Sub convertToPdfButton_Click(ByVal sender As Object, ByVal e As EventArgs)
    ' Create a HTML to PDF converter object with default settings
    Dim htmlToPdfConverter As New HtmlToPdfConverter()

    ' Set license key received after purchase to use the converter in licensed mode
    ' Leave it not set to use the converter in demo mode
    htmlToPdfConverter.LicenseKey = "4W9+bn19bn5ue2B+bn1/YH98YHd3d3c="

    ' Set an adddional delay in seconds to wait for JavaScript or AJAX calls after page load completed
    ' Set this property to 0 if you don't need to wait for such asynchcronous operations to finish
    htmlToPdfConverter.ConversionDelay = 2

    ' Select all images from HTML page
    htmlToPdfConverter.HtmlElementsMappingOptions.HtmlElementSelectors = New String() {"img"}

    ' Exclude the original images from rendering becuase they will be replaced by an image from local file system
    htmlToPdfConverter.HiddenHtmlElementsSelectors = New String() {"img"}

    Dim pdfDocument As Document = Nothing
    Try
        ' Convert a HTML string with images to replace to a PDF document object
        pdfDocument = htmlToPdfConverter.ConvertUrlToPdfDocumentObject(urlTextBox.Text)

        ' Replace the images selected in HTML using special attributes with images from local file system
        For Each imageElementInfo As HtmlElementMapping In htmlToPdfConverter.HtmlElementsMappingOptions.HtmlElementsMappingResult
            Dim imagePdfPage As PdfPage = imageElementInfo.PdfRectangles(0).PdfPage
            Dim imageRectangle As RectangleF = imageElementInfo.PdfRectangles(0).Rectangle

            Dim newImageElement As New ImageElement(imageRectangle.X, imageRectangle.Y, imageRectangle.Width, imageRectangle.Height, Server.MapPath("~/DemoAppFiles/Input/Images/box.jpg"))
            newImageElement.EnlargeEnabled = True
            imagePdfPage.AddElement(newImageElement)
        Next imageElementInfo

        ' Save the PDF document in a memory buffer
        Dim outPdfBuffer() As Byte = pdfDocument.Save()

        ' Send the PDF as response to browser

        ' Set response content type
        Response.AddHeader("Content-Type", "application/pdf")

        ' Instruct the browser to open the PDF file as an attachment or inline
        Response.AddHeader("Content-Disposition", String.Format("attachment; filename=Replace_with_Higher_Quality_Images.pdf; size={0}", outPdfBuffer.Length.ToString()))

        ' Write the PDF document buffer to HTTP response
        Response.BinaryWrite(outPdfBuffer)

        ' End the HTTP response and stop the current page processing
        Response.End()
    Finally
        ' Close the PDF document
        If pdfDocument IsNot Nothing Then
            pdfDocument.Close()
        End If
    End Try
End Sub