create image thumbnail with php codeigniter - php

Question

I am working on a codeigniter project where users can create profiles and upload their images..I want to create an image thumbnail (200 X 200) and save it in the directory. My code works perfectly as it uploads the image and also stores the image name in database but the problem is it does not resize the image..I want to resize all images (200 X 200) and then store them in directory.
This is controller
public function FunctionName()
{
$fname = ucwords($this->input->post('fname'));
$lname = ucwords($this->input->post('lname'));
$prof_pic = $_FILES['profile_pic']['name'];
$config = array ('upload_path' => './images/students/',
'allowed_types' => "jpeg|jpg|png",
'overwrite' => TRUE,
'file_name' => $Maxtype."_".$fname."_".$lname,
'remove_spaces' => TRUE,
'image_library' => gd2,
'source_image' => $prof_pic,
'new_image' => './images/students/',
'maintain_ratio' => TRUE,
'height' => 200,
'width' => 200
);
$this->load->library('upload', $config);
$this->upload->do_upload('profile_pic');
$extension = pathinfo($prof_pic);
$ext = $extension['extension'];
$image = $config['file_name'].".".$ext;
$data = array('std_fname' => $fname,
'std_lname' => $lname,
'profile_pic' => $image
);
}