<input type="hidden" id="y1" />
       <input type="hidden" id="w"  />
       <input type="hidden" id="h"  />
       <input id="SaveImgSrcValue" type="hidden" name="SaveImgSrcValue" />
   <img id="Img1" /><input id="Button1" type="button" value="生成头像" onclick="show();"  />
   </form>
</body>

</html>

ashx代码

<%@ WebHandler Language="C#" Class="UpLoadImg" %>
using System;
using System.Web;
using System.IO;
using System.Drawing;
public class UpLoadImg : IHttpHandler {
   public void ProcessRequest (HttpContext context)
   {
       context.Response.ContentType = "text/plain";
       context.Response.Expires = -1;
       try
       {
           HttpPostedFile postedFile = context.Request.Files["Filedata"];
           string savepath = "";