Images for lecture slides: licences, sources and attribution
An image found in a web search is copyrighted by default, and "it is for teaching" is not a licence in most places. Three routes are reliable: images under a Creative Commons licence or in the public domain, images your institution has licensed, and images you made. Prefer sources that record the licence per file — Wikimedia Commons, Openverse — because you can prove afterwards what you were allowed to do.
This guide covers the licences in plain terms, where to look, how to attribute, and the cases where none of it applies.
The licences, briefly
Creative Commons is a family, and the letters matter:
| Licence | What you may do | The catch |
|---|---|---|
| CC0 / public domain | anything, no attribution required | attribute anyway; it is polite and traceable |
| CC BY | use and adapt | credit the creator |
| CC BY-SA | use and adapt | credit, and share adaptations under the same licence |
| CC BY-NC | use and adapt | non-commercial only — check what your institution counts as commercial |
| CC BY-ND | use as-is | no adaptations, so no cropping or recolouring |
The current licences are version 4.0 and their terms are on the Creative Commons site; each licence page states exactly what attribution must contain. Two practical notes: NC is genuinely ambiguous for paid courses and executive education, so prefer BY or BY-SA for anything that might be commercial, and ND rules out the crop that would have made the figure fit your slide.
Where to look
- Wikimedia Commons — enormous, every file carries its licence and author on the file page, which is exactly what you need to cite.
- Openverse — searches across openly licensed collections and shows the licence with each result.
- Institutional subscriptions — many universities license an image or figure bank; the library page is the place to check, and the terms usually cover teaching use directly.
- Government and agency material — often public domain or openly licensed; check the specific agency.
- Figures from papers — not automatically reusable, even when you have access to the paper. Many publishers permit a figure in a lecture; some require a request. Check the publisher's permissions page or use the author's version if it carries an open licence.
Generated images are a moving target legally and vary by jurisdiction; if you use one in teaching material, say so on the slide.
Attribution that takes ten seconds
Put it on the slide with the image, small, not in a list at the end:
Figure: M. Yılmaz, "Diffraction pattern", Wikimedia Commons, CC BY-SA 4.0
Title, author, source, licence. That is the full requirement for most CC licences and it also tells students where to look for the original. The same rule as citing sources in slides: the citation belongs next to the claim.
For a course pack or anything that leaves the institution, keep a list of every image with its source and licence. It takes a minute per lecture and saves a week if anyone ever asks.
Screenshots, logos and student photographs
- Screenshots of software are usually acceptable for teaching about that software, but check the vendor's brand or press page.
- Logos and trademarks are not covered by image licences at all; use them to refer to the company, not as decoration.
- Photographs of people need consent, including photographs of your own students. A class photograph in a slide deck posted to an LMS is a different thing from one shown once in the room.
Keep the files with the course
Download the image, keep it in the week's folder, and record the source in a text file next to it — the layout in organising course materials. Hotlinking to someone else's server breaks in the middle of a lecture; a local file also matters for Marp PDF export, which needs --allow-local-files for local images.
FAQ
Can I use Google Images in a presentation?
Not as a source of rights. Search results are copyrighted by default; filter by usage rights and then verify the licence on the original page, or use a source that records licences.
What is the safest licence for teaching material?
CC0 and CC BY. Both allow use and adaptation; BY only requires credit. Avoid ND if you need to crop, and be careful with NC if the course is paid.
How do I credit an image on a slide?
Title, author, source and licence in small text on the same slide — for example "Figure: A. Author, Wikimedia Commons, CC BY 4.0".
Do I need permission to use a figure from a paper?
Often yes. Access to the paper is not permission to republish the figure; check the publisher's permissions terms or find an openly licensed version.