Read image from Generic Handler and allow users download it in ASP.Net

Hi

I am generating an image using handler and showing that image on image control. Now I want to download same image which is generated using handler. In my handler, I am passing imagepath and one querystring and retriving some data from database and watermark that content to my image. Kindly let me know how to download that same image.

Code:

 protected void Page_Load(object sender, EventArgs e)
    {
        if (Request.QueryString.HasKeys())
        {
            string Code = Request.QueryString["Code"].ToString();
          
            Session["Code"] = Code;
            imgCoupon.ImageUrl = String.Format("ImageHandler.ashx?ImageUrl=" + Server.MapPath("Images/coupon.jpg") + "&Code=" + Code + "");
            Code = null;
        }
        else
        {
            lblmsg.Text = "No Code Found";
        }
        
    }
    protected void btnDownload_Click(object sender, EventArgs e)
    {
        Response.ContentType = "image/jpeg";

        Response.AppendHeader("Content-Disposition", "attachment; filename=" + Session["Code"].ToString() + ".jpg");

    

        Response.End();
    }