Here are some initial factors to consider:
- Are we an educational institution?
- Are we a non-profit organization?
- Is this work going to be used in the classroom?
However, if you’re going to post material to a public website, use it in a publication, or reproduce and distribute it in any way (including email), you must seek written permission to use the very same work you may have shown to your class last week. You may have to pay for this permission. If you work in an academic support area, then you must seek permission. Any use outside of the classroom requires permission.
On a related note, material (like a film) used for an event, or a club meeting, or anything on-campus outside of an official class meeting attended only by enrolled class members, also requires--not only permission-- but the payment of public performance fees as well.
The library maintains a list of Images and Image Galleries: on it are resources that may be used for individual research or educational purposes. You’ll also find links to the resources’ legal permissions and copyright information pages where you can investigate requirements for other uses of their visual material.