User.php

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class User extends CI_Controller{
    public function check_captcha($captcha_input)
    {
        // First, delete old captchas
        $expiration = time() - 7200; // Two hour limit
        $this->db->where('captcha_time < ', $expiration)
                ->delete('captcha');

        // Then see if a captcha exists:
        $sql = 'SELECT COUNT(*) AS count FROM captcha WHERE word = ? AND ip_address = ? AND captcha_time > ?';
        $binds = array($captcha_input, $this->input->ip_address(), $expiration);
        $query = $this->db->query($sql, $binds);
        $row = $query->row();
        if ($row->count == 0){
            $this->form_validation->set_message('check_captcha', 'Captcha Fail');
            return FALSE;
        }else {
            return TRUE;
        }

    }

    public function register(){
        $this->form_validation->set_rules('user_name' , 'Username' , 'trim|required|max_length[32]');
        $this->form_validation->set_rules('captcha' , 'Captcha' , 'trim|required|max_length[32]|callback_check_captcha');
        $this->form_validation->set_rules('password', 'Password','trim|required|min_length[5]|max_length[12]');
        $this->form_validation->set_rules('confirm_password', 'Confirm Password','trim|required|min_length[5]|max_length[12]|matches[password]');
        $this->form_validation->set_rules('email', 'Email', 'trim|required|valid_email');
        if ($this->form_validation->run()==FALSE){
        //Captcha code
        $this->load->helper('captcha');
        //Captcha Config
        $vals = array(
            'img_path'      => './captcha',
            'img_url'       => './captcha/',
            'img_width'     => '150',
            'img_height'    => 30,
            'expiration'    => 7200,
            'word_length'   => 8,
            'font_size'     => 16,
            'img_id'        => 'Imageid',
             'font_path'     => '/fonts/Open.ttf',

            // White background and border, black text and red grid
            'colors'        => array(
                    'background' => array(255, 255, 255),
                    'border' => array(255, 255, 255),
                    'text' => array(0, 0, 0),
                    'grid' => array(255, 40, 40)
            )
        );
        //Create the Captcha
        $cap = create_captcha($vals);

        // Store The Created Captcha in DB for Verification
        $data = array(
        'captcha_time'  => $cap['time'],
        'ip_address'    => $this->input->ip_address(),
        'word'          => $cap['word']
        );
        $this->register_model->store_captcha($data);
        //Load View
        $data['image']=$cap['image'];
        var_dump($data['image']);exit();
        $this->load->view('templates/header');
        $this->load->view('register' , $data);
        $this->load->view('templates/footer');
        }else {
                  $option=array('cost'=>12);
                  $encrypt_password=password_hash($this->input->post('password'),PASSWORD_BCRYPT,$option);
                  $this->register_model->add_user($encrypt_password);
                  $this->session->set_flashdata('user_registered','You are Successfully Registered and can Log in ');
                  redirect('register/success');
        }
    }
    public function success(){
        $this->load->view('success');
    }
}

View (register.php)

<div class="col-md-8">
    <h2>Register</h2><br>
    <?php echo validation_errors(); ?>
    <?php echo form_open("register");

    ?>
      <div class="form-group">
        <label>Enter UserID</label>
        <input type="text" class="form-control" name="user_name"  placeholder="Enter Your UserId">
      </div>
      <div class="form-group">
        <label>Enter Your Email</label>
        <input type="email" class="form-control" name="email"  placeholder="Enter Your Email">
      </div>
      <div class="form-group">
        <label>Enter Your Password </label>
        <input type="password" class="form-control" name="password"  placeholder="Enter Password">
      </div>
      <div class="form-group">
            <label>Re-enter Password </label>
            <input type="password" class="form-control" name="confirm_password"  placeholder="Renter Password">
      </div>
      <?php echo $image ; ?>
      <div class="form-group">
            <label>Solve Captcha </label>
            <input type="text" class="form-control" name="captcha" >
      </div>
       <button type="submit" class="btn btn-primary">Submit</button>
      <?php echo form_close();?>
</div>