How to get good quality image during chart to image or PDF conversion in C#, VB.NET?

//Set the image quality
application.ChartToImageConverter.ScalingMode = ScalingMode.Best;

using Syncfusion.ExcelChartToImageConverter;
using Syncfusion.XlsIO;
using System.Drawing;
using System.IO;
 
namespace ImageQuality
{
  class Program
  {
    static void Main(string[] args)
    {
      using (ExcelEngine excelEngine = new ExcelEngine())
      {
            //Instantiate the excel application object
 IApplication application = excelEngine.Excel;
 
            //Set default version
 application.DefaultVersion = ExcelVersion.Excel2013;
 
 //Initializing the chart to image converter object
 application.ChartToImageConverter = new ChartToImageConverter();
 
 //Set the image quality
 application.ChartToImageConverter.ScalingMode = ScalingMode.Normal;
 
 //Open existing workbook with data entered
 Assembly assembly = typeof(Program).GetTypeInfo().Assembly;
 Stream fileStream = assembly.GetManifestResourceStream("ImageQuality.Sample.xlsx");
 IWorkbook workbook = application.Workbooks.Open(fileStream);
 
 //The first worksheet object in the worksheets collection is accessed
 IWorksheet worksheet = workbook.Worksheets[0];
 
 //The first chart object in the charts collection is accessed
 IChart chart = worksheet.Charts[0];
 
 //Creating the memory stream for chart image
 MemoryStream stream = new MemoryStream();
 
 //Saving the chart as image
 chart.SaveAsImage(stream);
 
 //Getting the image file from stream
 Image image = Image.FromStream(stream);
 
 //Saving image stream to file
 image.Save("Output.png");
      }
    }
  }
}

Imports System.Drawing
Imports System.IO
Imports Syncfusion.ExcelChartToImageConverter
Imports Syncfusion.XlsIO
 
Namespace ImageQuality
  Class Program
    Public Shared Sub Main(ByVal args As String())
      Using excelEngine As ExcelEngine = New ExcelEngine()
 'Instantiate the excel application object
 Dim application As IApplication = excelEngine.Excel
 
 'Set default version
 application.DefaultVersion = ExcelVersion.Excel2013
 
 'Initializing the chart to image converter object
 application.ChartToImageConverter = New ChartToImageConverter
 
 'Set the image quality
 application.ChartToImageConverter.ScalingMode = ScalingMode.Best
 
 'Open existing workbook with data entered
 Dim assembly As Assembly = GetType(Program).GetTypeInfo.Assembly
 Dim fileStream As Stream = assembly.GetManifestResourceStream("ImageQuality.Sample.xlsx")
 Dim workbook As IWorkbook = application.Workbooks.Open(fileStream)
 
 'The first worksheet object in the worksheets collection is accessed
 Dim worksheet As IWorksheet = workbook.Worksheets(0)
 
 'The first chart object in the charts collection is accessed
 Dim chart As IChart = worksheet.Charts(0)
 
 'Creating the memory stream for chart image
 Dim stream As MemoryStream = New MemoryStream
 
 'Saving the chart as image
 chart.SaveAsImage(stream)
 
 'Getting the image file from stream
 Dim image As Image = Image.FromStream(stream)
 
 'Saving image stream to file
 image.Save("Output.png")
      End Using
    End Sub
  End Class
End Namespace