Retrieve image of differnt format from database, using generic handler

using System;
using System.Web;
using System.IO;
public class Handler : IHttpHandler {
    
    public void ProcessRequest (HttpContext context) 
    {
        Int32 regno;
        if (context.Request.QueryString["id"] != null)
            regno = Convert.ToInt32(context.Request.QueryString["id"]);
        else
            throw new ArgumentException("No parameter specified");

        context.Response.ContentType = "image/jpeg";
        Stream strm = ShowImage(regno);
        byte[] buffer = new byte[4096];
        int byteSeq = strm.Read(buffer, 0, 4096);

        while (byteSeq > 0)
        {
            context.Response.OutputStream.Write(buffer, 0, byteSeq);
            byteSeq = strm.Read(buffer, 0, 4096);
        }
        context.Response.BinaryWrite(buffer);
    }

    public Stream ShowImage(int regno)
    {
        System.Data.DataTable dt = Student.getStudentData(regno.ToString());
        //if (dt.Rows.Count > 0)
        //{
            object imgP = dt.Rows[0]["imgattach_p"];
            
            try
            {
                return new MemoryStream((byte[])imgP);
            }
            catch
            {
                return null;
            }
        //}
        
    }
    
 
    public bool IsReusable {
        get {
            return false;
        }
    }