I am using link_to img tag like following
<%= link_to image_tag(\"Search.png\", :border=>0, :class => \'dock-item\'), :action => \'search\', :co
Easy:
<%= link_to image_tag("Search.png", :border=>0), :action => 'search', :controller => 'pages', :class => 'dock-item' %>
The first param of link_to is the text/html to link (inside the a tag). The next set of parameters is the url properties and the link attributes themselves.