How to convert Excel to Image with Azure V3 function?

using Syncfusion.XlsIO;
using Syncfusion.XlsIORenderer;
using System.Net.Http;
using System.Net;
using System.Net.Http.Headers;
using Microsoft.Azure.WebJobs.Host;

Stream stream = req.Content.ReadAsStreamAsync().Result;
//Instantiate the spreadsheet creation engine
using (ExcelEngine excelEngine = new ExcelEngine())
{
    IApplication application = excelEngine.Excel;
    application.DefaultVersion = ExcelVersion.Excel2013;
    IWorkbook workbook = application.Workbooks.Open(File.OpenRead("../../Template.xlsx"), ExcelOpenType.Automatic);
    IWorksheet sheet = workbook.Worksheets[0];
 
    //Initialize XlsIORenderer 
    application.XlsIORenderer = new XlsIORenderer();
 
    //The stream to save the converted image 
    MemoryStream memoryStream = new MemoryStream();
 
    //Convert the worksheet’s used range to an image 
    sheet.ConvertToImage(sheet.UsedRange.Row, sheet.UsedRange.Column, sheet.UsedRange.LastRow, sheet.UsedRange.LastColumn, memoryStream);
 
    //Create the response to return
    HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
 
    //Set the PDF document content response
    response.Content = new ByteArrayContent(memoryStream.ToArray());
 
    //Set the contentDisposition as attachment
    response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
    {
        FileName = "Output.png"
    };
    //Set the content type as PDF format mime type
    response.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("image/png");
 
    //Return the response with output PDF stream
    return response;
}

//Open the required template Excel file
Stream fileStream = File.Open("../../Data/Template.xlsx", FileMode.Open);
 
//Create memory stream to save the template
MemoryStream inputStream = new MemoryStream();
 
//Copy the file stream into memory stream
fileStream.CopyTo(inputStream);
 
//Dispose the file stream
fileStream.Dispose();
try
{
    //Create HttpWebRequest with hosted azure function URL
    HttpWebRequest req = (HttpWebRequest)WebRequest.Create("https://azurefunction20210504163552.azurewebsites.net");
 
    //Set request method as POST
    req.Method = "POST";
 
    //Get the request stream to strore the Excel document stream
    Stream stream = req.GetRequestStream();
 
    //Write the Excel document stream into request stream
    stream.Write(inputStream.ToArray(), 0, inputStream.ToArray().Length);
 
    //Gets the responce from the Azure Function request
    HttpWebResponse res = (HttpWebResponse)req.GetResponse();
 
    //Create file stream to save the output PDF file
    FileStream outStream = File.Create("Sample.png");
 
    //Copy the responce stream into file stream
    res.GetResponseStream().CopyTo(outStream);
 
    //Dispose the input stream
    inputStream.Dispose();
 
    //Dispose the file stream
    outStream.Dispose();
}
catch (Exception ex)
{
    throw;
}
 
//Launch the output document
System.Diagnostics.Process.Start("Sample.png");