When using Copyrighted work with written permission from owner…
Ex. Used with permission from Silvia Tolisano http://langwitches.org/blog/wp-content/uploads/2014/02/google-glass-recording-225×225.jpg
When using images licensed under Creative Commons…
Ex. Image licensed under Creative Commons by langwitches- http://langwitches.org/blog/2014/02/13/google-glass-recording-at-schools/
When using an image falling under Public Domain, you are not required to cite the creator/owner of the work. A teacher or student wanting to model awareness for Public Domain might want to choose to include.
When using images claiming Fair Use, you have to give full credit to original creator , with name as well as link to original source (ex. Book or website)