Remove Existing Self Linking Images ("WP Selfies") in WordPress. See http://cfxdesign.com/remove-existing-self-linking-images-in-wordpress

remove_wp_selfies.php

<?php

function remove_self_linking_images() {
  $all_ids = new WP_Query(array(
    'post_type'      => array('post', 'page'), // feel free to add custom post types here if necessary
    'posts_per_page' => -1,
    'post_status'    => 'any',
    'fields'         => 'ids'
  ));

  foreach($all_ids->posts as $id) {
    $current_post     = get_post($id);
    $current_content  = $current_post->post_content;
    $content_replaced = $current_content;

    preg_match_all('/<a.*?href=\"(.*?)\".*?>(<img.*?src=\"(.*?)\".*?>)<\/a>/', $current_content, $matches);

    $wp_selfies = $matches[0];

    if(count($wp_selfies) > 0) {
      $wp_selfies_urls = $matches[1];
      $wp_selfies_imgs = $matches[2];
      $wp_selfies_srcs = $matches[3];

      foreach($wp_selfies as $key => $selfie) {
        if($wp_selfies_urls[$key] === $wp_selfies_srcs[$key]) {
          $content_replaced = str_replace($selfie, $wp_selfies_imgs[$key], $content_replaced);
        }
      }

      wp_update_post(array(
        'ID'           => $id,
        'post_content' => $content_replaced
      ));
    }
  }
}
//add_action('admin_init', 'remove_self_linking_images');