Convert base 64 string to image file

hi

This is how i am doing the function(GetImagePAth) is getting called but when i am uploading big images the server side method is not getting called

function upload() {
try {
var sImage = document.getElementById('uploadPreview').src;

// i am getting base 64 string in sImage
//temporary post base 64 string save that base 64 string as image file and return the path thas all
$.ajax({
type: "POST",
url: "EmailCampaignEditor.aspx/GetImagePAth",
data: '{name: "' + sImage + '" }',
contentType: "application/json; charset=utf-8",
dataType: "json",
success: OnSuccess,
failure: function(response) {
alert(response.d);
}
});
//temporary

}
catch (Error) {
}
}

function OnSuccess(response) {
alert(response.d);
}


[System.Web.Services.WebMethod]
public static string GetImagePAth(string base64string)
{
EmailCampaignEditor em = new EmailCampaignEditor();
Page p = new Page();

string BaseURL = "";
string path = "";
string matchString = "";
try
{
byte[] imageByteArray = Convert.FromBase64String(base64string.Split(',').ToArray()[1]);
MemoryStream ms = new MemoryStream(imageByteArray, 0, imageByteArray.Length);
ms.Write(imageByteArray, 0, imageByteArray.Length);
//return System.Drawing.Image.FromStream(ms, true);

using (Bitmap bm2 = new Bitmap(ms))
{
string ImgPath = "~\\View\\Images\\";

string iPath = em.ServerMappath(ImgPath);

bm2.Save(iPath + campname + EmailCampaignEditor.imgn + "ImageName.jpg");


path = campname + EmailCampaignEditor.imgn + "ImageName.jpg";


BaseURL = "http://" + path_64 + "/View/Images/" + path;
EmailCampaignEditor.imgn++;
}
}
catch (Exception ex)
{

return matchString;
}

return BaseURL;
}