image save in databse and display jquery c#

FileUpload11 and btnupload inside datalist.

code not work error show

error during serialization or deserialization using the JSON java scriptserialzier. The length of string exceeds the value set on the maxjson length property

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script type="text/javascript">
       $(function () {
           var reader = new FileReader();
           var fileName;
           var contentType;
           $('input[type=file]').change(function () {
               if (typeof (FileReader) != "undefined") {
                   var regex = /^([a-zA-Z0-9\s_\\.\-:])+(.jpg|.jpeg|.gif|.png|.bmp)$/;
                   $($(this)[0].files).each(function () {
                       var file = $(this);
                       if (regex.test(file[0].name.toLowerCase())) {
                           fileName = file[0].name;
                           contentType = file[0].type;
                           reader.readAsDataURL(file[0]);
                       } else {
                           alert(file[0].name + " is not a valid image file.");
                           return false;
                       }
                   });
               } else {
                   alert("This browser does not support HTML5 FileReader.");
               }
           });
 
           $('#btnUpload').on("click", function () {
               var byteData = reader.result;
               byteData = byteData.split(';')[1].replace("base64,", "");
               $.ajax({
                   type: "POST",
                   url: "Default12.aspx/InsertImage",
                   data: '{byteData: "' + byteData + '", imageName: "' + fileName + '", contentType: "' + contentType + '" }',
                   contentType: "application/json; charset=utf-8",
                   dataType: "json",
                   success: function (response) { alert(response.d); },
                   error: function (response) { alert(response.responseText); }
               });
               return false;
           });
       });
</script>