private function _getImageTypeFromFileName($imageFile)
    {
        $ext = strtolower((string)pathinfo($imageFile, PATHINFO_EXTENSION));

        if ('jpg' === $ext or 'jpeg' === $ext) {
            return ImageType::JPEG;
        } else if ('gif' === $ext) {
            return ImageType::GIF;
        } else if ('png' === $ext) {
            return ImageType::PNG;
        } else if ('wbm' === $ext or 'wbmp' === $ext) {
            return ImageType::WBMP;
        } else {
            return ImageType::UNKNOWN;
        }
    }