Display a generated gif;base64 image using C# code behind in img using JavaScript

i have the following C# code behind (it is a code that generate dynamically an Bmp image and than convert it to gif and returns it to be displayed):

[WebMethod]
public static HtmlImage ProcessIT()
{
var bitmap = DrawingMethod(); //Method that draws dynamically Bmp Image 
MemoryStream ms = new MemoryStream();
bitmap.Save(ms, ImageFormat.Jpeg);
var base64Data = Convert.ToBase64String(ms.ToArray());
HtmlImage img = new HtmlImage 
{Src = "data:image/gif;base64," + base64Data, Width = 940};
return img; //The Gif image i want to display on the page
}

Than, I'm calling this C# behind code Method from : Generate_onclick() which is a JavaScript

function Generate_onclick() 
{
  PageMethods.ProcessIT(onSucess, onError);
   function onSucess(result) 
    {
     //Here is where i am not sure how it's done !!!!!!
     document.getElementById("imgCtrl").src = result; 
    }

   function onError(result) 
    {
      alert('Something wrong.');
    }
}

in here is the HTML Code :

<img src="" alt="" style="width: 100%;" runat="server" id="imgCtrl" />

is this the right way to display my image in the page ? if not than how ?