<asp:Button ID="Button1" runat="server" Text="Get PDF Image" 

            CssClass="btn"

            OnClick="Button1_Click"                

            />

        <br />

        <br />

        <asp:Image ID="Image1" runat="server" Height="215px" Width="334px" />

    protected void Page_Load(object sender, EventArgs e)

    {

    }

    protected void Button1_Click(object sender, EventArgs e)

    {

        string strF = @"c:\test\CONTROL.pdf";

        byte[] MyBytePic = GetPdfThumb(strF);

        string sMineType = MimeMapping.GetMimeMapping("abc.jpeg");

        Image1.ImageUrl =

                $@"data:{sMineType};base64,{Convert.ToBase64String(MyBytePic)}";

    }

    public byte[] GetPdfThumb(string strPDF)

    {

        Ghostscript.NET.GhostscriptVersionInfo gVER;

        string strgDLL = System.Web.HttpContext.Current.Server.MapPath(@"~\MyDLL") + @"\gsdll64.dll";

        gVER = new Ghostscript.NET.GhostscriptVersionInfo(new Version(0, 0, 0), 

                    strgDLL, "", Ghostscript.NET.GhostscriptLicense.GPL);

        using (GhostscriptRasterizer gPDF = new GhostscriptRasterizer())

        {

            using (MemoryStream fs = new MemoryStream())

            {

                try

                {

                    gPDF.Open(strPDF, gVER, true);

                    gPDF.GetPage(18, 1).Save(fs, ImageFormat.Jpeg);

                    gPDF.Close();

                    fs.Close();

                    return fs.ToArray();

                }

                catch (Exception ex)

                {

                    Debug.Print(ex.Message);

                    return new byte[0];

                }

            }

        }

    }