I have a mobile app that applies filters to user photos. Suppose that i want to add a filter (or a set of filters) named "Gotham" or "Daredevil" or "X-Men". Suppose this filter (or set of filters) are available only after the user purchases it (that is, they are in app purchases). Does this use of trademarked words constitues a trademark infringement? My guess is that this should not be a trademark infringement, since there is no possible confusion of the source of good.