pop up window not getting post value

Use row_array() in your model, not result_array(), since you only need to get one record.

PHP Code:

public function get_by_id1($markid)
{
    //$response = array();   // this line makes no sense
    $query = $this->db->where('markid',$markid)->get('upload');
    return $query->row_array();  
}