    def to_html(output=false, options={})
      html = ''
      options = @options.merge(options)
      files = output_directory
      @builder = Builder.new(@contents) do |builder|
        builder.title = @path.basename
        builder.files = files.relative_path_from(files.dirname)
        builder.style = options[:style] if options.has_key?(:style)
        # option
        builder.indecies = @indecies.dup
        builder.references = @references.dup

        html = builder.build_html
      end
      if output
        create_files if has_image?
        html_file = output_file(:html)
        File.open(html_file, 'w:utf-8') do |f|
          f.puts html
        end
      end
      html
    end