Copyright applies to images as well as to written works, which means that the same policies apply:
Cartoons are treated like any other image for copyright. For use outside the classroom, permission must be obtained from the copyright holder. Cartoon copyright owners generally have very visible copyright policies on their web sites.
You are responsible for copyright permission for your own web site.
For Faculty library staff can create a Readings only Blackboard page that can be linked directly to your web site. In this instance we take care of copyright permissions.