function next_image(nos)
{
    var no_series=4;
    var no_images="gallery1.jpg,gallery2.jpg,gallery3.jpg,gallery4.jpg";
    var image_list=no_images.split(",");
    
    if(nos==1)
    {
        document.getElementById("id1").innerHTML='<img src="images/gallery_arr_left1.gif" width="20" height="115" border="0" />';    
    }
    if(nos!=1)
    {
       var int_nos_new=nos;
       int_nos_new--;
      document.getElementById("id1").innerHTML='<a href="#" onclick="return next_image('+int_nos_new+')">'+
    '<img src="images/gallery_arr_left.gif" width="20" height="115" border="0" /></a>';
    }
    if(no_series!=nos)
    {
       var int_nos=nos;
       int_nos++;
        document.getElementById("id2").innerHTML='<a href="#" onclick="return next_image('+int_nos+')">'+
    '<img src="images/gallery_arr_right.gif" width="24" height="115" border="0" /></a>';
    }
    if(no_series==nos)
    {
        document.getElementById("id2").innerHTML='<img src="images/gallery_arr_right1.gif" width="24" height="115" border="0" />';
    }
    
    document.banner1.src='images/'+image_list[nos-1];
    return true;
}