    # File lib/action_view/helpers/asset_tag_helper.rb, line 489
          def image_tag(source, options = {})
            options.symbolize_keys!

            options[:src] = path_to_image(source)
            options[:alt] ||= File.basename(options[:src], '.*').split('.').first.to_s.capitalize

            if size = options.delete(:size)
              options[:width], options[:height] = size.split("x") if size =~ %r{^\d+x\d+$}
            end

            if mouseover = options.delete(:mouseover)
              options[:onmouseover] = "this.src='#{image_path(mouseover)}'"
              options[:onmouseout]  = "this.src='#{image_path(options[:src])}'"
            end

            tag("img", options)
          end