Images of all sorts--photographs, prints, paintings, illustrations, diagrams, graphs, maps, film, videos, digital or not--are protected by copyright just as other materials are.
First, determine if the image you want to use is in the public domain or available from a licensed resource.
The exemption for classroom use (Section 110) allows the limited display of images in the classroom or in the online teaching environment. See Classroom Performance/Display and TEACH Act.
For other uses of images, conduct a fair use analysis to see if your proposed use would require permission.
- You may be dealing with layers of images: e.g. a digital reproduction of a book illustration or photograph. Although the original may be in the public domain, the digital reproduction may still be covered by copyright or license.
- The fair use principles allow for the use of a portion of a work, but an image may be an entire work in itself. Note that illustrations in books and articles may be individually copyrighted separately from the book/article. The Fair Use Guidelines for Educational Multimedia recommend using no more than 5 works by the same artist/photographer or no more than 15 images or 10% from a collective work (whichever is less), but also have restrictions on where and for how long these works can be used. They also recommend using no more than "10% or 3 minutes, whichever is less, in the aggregate of a copyrighted motion media work."
- Copyright protects creative expression, so an image that displays more individual expression is more protected than a more generic depiction. A dramatic film is more protected than an instructional film or news broadcast.
- The purpose of your use is important. The use of images integral for teaching, comment, critique, or to illustrate a point would be more favored than a merely decorative or supplementary use.