change show method image thumb size

app/controllers/galleries_controller.rb

@@ -24,7 +24,7 @@ class GalleriesController < ApplicationController
 	    {
         "image-description" => a.description,
 	     "link_to_show" =>  "/" + I18n.locale.to_s + params[:url] + "/-" + a.id.to_s + "?method=theater",
-	     "thumb-src" => a.file.thumb.url
+	     "thumb-src" => a.file.thumb_fixed_width.url
 	    }
 	   end
       {