Your server does not support the GD function required to process this type of image.Ci

During my project I faced similar problem. This link help me to solve it.

Replace

$this->load->library('image_lib', $config);

with

$this->load->library('image_lib');
// Set your config up
$this->image_lib->initialize($config);
// Do your manipulation
$this->image_lib->clear();

change your first lines from:

$original_path = './uploads/activity_images/original';
$resized_path = './uploads/activity_images/resized';
$thumbs_path = './uploads/activity_images/thumb';
$this->load->library('image_lib');

to:

$config['image_library'] = 'gd2';
$original_path = './uploads/activity_images/original';
$resized_path = './uploads/activity_images/resized';
$thumbs_path = './uploads/activity_images/thumb';
$this->load->library('image_lib', $config);