unable to resize an image using codeigniter

I'm using CodeIgniter v3.1.6.My project directory structure is as follows:

-application
-assets
-system
........

I want to resize an image (939128_1523936489.jpg) originally located at assets/admin/uploads/editionpages_img My resize code is as follows:

function __construct()
{
   $this->load->library('image_lib');
   $this->load->helper("url");
   $this->load->helper('form');

}

public function resize()
{
            $imgName ='939128_1523936489';
            $config['image_library'] = 'gd2';
            $config['source_image'] = './assets/admin/uploads/editionpages_img/'.$imgName.".jpg";
            $config['new_image'] = './assets/admin/uploads/editionpages_img/'.$imgName."_new.jpg";
            $config['create_thumb'] = TRUE;
            $config['maintain_ratio'] = TRUE;
            $config['width'] = 50;
            $config['height'] = 50;

            $this->load->library('image_lib', $config);
            if (!$this->image_lib->resize()) {
                echo $this->image_lib->display_errors();
            }

            $this->image_lib->clear();

}

When this code is run, no error is shown neither any resized image is created at the above location.Please advise what is wrong with my code.Thanks.

Hope this will solve your problem

Note : the folder containing the image files must have write permissions.

First : remove image_lib form the constructor method

function __construct()
{
   $this->load->helper("url");
   $this->load->helper('form');

}

Second : add FCPATH in resize() method

your method should be like this :

public function resize()
{
    $imgName ='939128_1523936489';
    $config['image_library'] = 'gd2';
    $config['source_image'] = FCPATH.'assets/admin/uploads/editionpages_img/'.$imgName.".jpg";
    $config['new_image'] = FCPATH.'assets/admin/uploads/editionpages_img/'.$imgName."_new.jpg";
    $config['create_thumb'] = TRUE;
    $config['maintain_ratio'] = TRUE;
    $config['width'] = 50;
    $config['height'] = 50;

    $this->load->library('image_lib', $config);
    if (!$this->image_lib->resize()) {
        echo $this->image_lib->display_errors();
    }

    $this->image_lib->clear();
}

For more : https://www.codeigniter.com/user_guide/libraries/image_lib.html