public function createDefaultThumbs($image = null, $app = 'default')
    {
        if(!$image) {
            $image = $this;
        }

        if($image->hasImageExtension()) {
            foreach (config('media.default_thumb_size') as $thumKey => $thumValue) {
                if ($thumKey == "default" || $thumKey == $app) { // create only the thumbs that are needed for an app
                    foreach ($thumValue as $thumbDimension) {
                        $this->createThumb($image, $thumbDimension[0], $thumbDimension[1]);
                    }
                }
            }
        }

        return $this;
    }