/**
  * Fired when the plugin is activated.
  *
  * @since    1.0.0
  *
  * @param    boolean    $network_wide    True if WPMU superadmin uses "Network Activate" action, false if WPMU is disabled or plugin is activated on an individual blog.
  */
 public static function activate($network_wide)
 {
     $class = Original_Image_Handler::get_instance();
     if (get_option('oih_auto_convert_bmp', 'NotExistingValue') == 'NotExistingValue') {
         //If the setting has not been set before
         update_option('oih_auto_convert_bmp', $class->default_auto_convert_bmp);
     }
     if (get_option('oih_remove_original_after_resizing', 'NotExistingValue') == 'NotExistingValue') {
         update_option('oih_remove_original_after_resizing', $class->default_remove_original_after_resizing);
     }
     if (get_option('oih_max_image_width', 'NotExistingValue') == 'NotExistingValue') {
         update_option('oih_max_image_width', $class->default_max_image_width);
     }
     if (get_option('oih_max_image_height', 'NotExistingValue') == 'NotExistingValue') {
         update_option('oih_max_image_height', $class->default_max_image_height);
     }
     if (get_option('oih_bmp_conversion_quality', 'NotExistingValue') == 'NotExistingValue') {
         update_option('oih_bmp_conversion_quality', $class->default_bmp_conversion_quality);
     }
     if (get_option('oih_start_upload_size', 'NotExistingValue') == 'NotExistingValue') {
         $upload_path = wp_upload_dir();
         $output = $class->calculate_upload_dir($upload_path['basedir']);
         update_option('oih_start_upload_size', $output);
         update_option('oih_current_upload_size', $output);
     }
 }
<?php

/**
 * @package   original-image-handler
 * @author    Internetbureau Haboes <*****@*****.**>
 * @license   GPL-2.0+
 * @link      http://www.haboes.nl
 * @copyright 2013 Internetbureau Haboes
 *
 * @wordpress-plugin
 * Plugin Name: Original Image Handler
 * Plugin URI:  http://www.haboes.nl
 * Description: After uploading an file it will resize and remove the original file from the server to save diskspace. It also converts BMP files to JPEG files to save diskspace.
 * Version:     1.0.0
 * Author:      Internetbureau Haboes B.V.
 * Author URI:  http://www.haboes.nl
 * Text Domain: oih
 * License:     GPL-2.0+
 * License URI: http://www.gnu.org/licenses/gpl-2.0.txt
 * Domain Path: /lang
 */
// If this file is called directly, abort.
if (!defined('WPINC')) {
    die;
}
require_once plugin_dir_path(__FILE__) . 'class-original-image-handler.php';
// Register hooks that are fired when the plugin is activated, deactivated, and uninstalled, respectively.
register_activation_hook(__FILE__, array('Original_Image_Handler', 'activate'));
Original_Image_Handler::get_instance();