It is important to correctly attribute any images you use. Unless the images have been provided by a service which has specifically told you that you do not need attribution, provide the creator's name, title, URL and the type of Creative Commons license if available.
Think TASL: Title, Author, Source, License
Bare minimum:
Image by GDW.45 [CC BY-SA 3.0]
Best practice:
Image: Blue Winged Kookaburra by GDW.45, CC BY-SA 3.0.
N.B. The above is best practise if you can link to the source in the title (f possible, you should also try to link to the creator's details from their name). If you are producing a print work and cannot link out, also include the source. For example: Blue Winged Kookaburra by GDW.45, from Wikimedia, CC BY-SA 3.0.
Please Note:
Some referencing styles (like APA) have specific requirements for acknowledging the copyright holders for images. If you are preparing a document according to a particular style, find out what that style requires for referencing and acknowledgment.
Attribution vs Referencing
Some image licenses do not require attribution (e.g. CC0, Unsplash licenses, some Morguefile licenses). This is not relevant for referencing in assignments. In an assignment, you should cite all of your sources, even if they are marked as not requirig an attribution.
We acknowledge the Australian Aboriginal and Torres Strait Islander peoples as the first inhabitants of the nation and acknowledge Traditional Owners of the lands where our staff and students, live, learn and work.