wiki_external_filter/app/views/wiki_external_filter/macro_image.html.erb

<img <%= render_type == 'inline' ? "class='externalfilterinline'" : "" %> src='<%= url_for(:controller => 'wiki_external_filter', :action => 'filter', :macro => macro, :name => name, :index => 0) %>' alt="<%= h source %>" />