change image size without changing the resolution

Hi Experts,
i created a simple code in C# to generate QRCode image size 197x197 for employees, my question is how to change the size without losing the quality.

protected void Page_Load(object sender, EventArgs e)
        {
            //--read employees information            
            string text, strSQL;
            strSQL = "select CPRNo, EngName,'1757' + OfficeTel as Tel,FaxNo,EmpEmail from GetUserDetailsE where PERUserName='mffinjm' ";
            EmpInfo empinfo = new EmpInfo();
            SqlDataReader sqlReader = null;
            using (SqlConnection con = GetConnectedPr())
            {
                SqlCommand myCommand = new SqlCommand(strSQL, con);
                sqlReader = myCommand.ExecuteReader();
                while (sqlReader.Read())
                {
                    empinfo.CPR = sqlReader["CPRNo"].ToString();
                    empinfo.EngName = sqlReader["EngName"].ToString();
                    empinfo.Tell = sqlReader["Tel"].ToString();
                    empinfo.email = sqlReader["EmpEmail"].ToString();
                    empinfo.Fax = sqlReader["FaxNo"].ToString();
                 }
             }                            
            //--Create QRCode
            QRCodeEncoder encoder = new QRCodeEncoder();
            text = "N:" +empinfo.EngName + ";TEL:"+ empinfo.Tell +";URL:http://www.mof.gov.bh;EMAIL:"+ empinfo.email +
                ";FAX:" + empinfo.Fax + ";NOTE:Ministry of Finance";
            Bitmap img = encoder.Encode(text);            
            img.Save(Server.MapPath("/images/"+ empinfo.CPR +".jpg"), ImageFormat.Jpeg);
            QRImage.ImageUrl = "~/images/" + empinfo.CPR + ".jpg";                  
        }

Select allOpen in new window

any suggestion

thank you