The Extending ELT section on the Hub provides links to public domain, copyright free and creative commons image, sound and video repositories. Such repositories can be a valuable resource for sourcing digital content to supplement online teaching and learning materials.
Take me to the list of links to digital media repositories 
The following documentation offers advice, guidance and recommendations on the sourcing and use of digital content that has been downloaded from online repositories.
Even though a digital content repository reports to contain copyright free content, it is still important to check that the licensing information supplied with the individual item of content (image, audio recording, video) allows you to use it in the way that you want. For example:
This is an image from a public domain image resource:
The licensing information provided with the image is as follows:
In this case it is very clear as to how you may re-use this image.
If you cannot find any information accompanying the digital content that states what rights you have in copying and reusing the content, then it is best to err on the side of caution and not use the content in any internet-based teaching and learning resource – this includes Blackboard.
IMPORTANT NOTE on downloading and using photographs of people.
You MUST check that the person who took the original photograph of the person(s) secured a model release for the photo – meaning that the person(s) in the photograph agreed to allow the photograph to be made available for others to use. In the example above it is clear in the licensing information that the photographer did obtain a model release for the image. If a model release has not been obtained, or you are unsure if one has or hasn’t, then you should not use the image.
It is recommended that where possible you should use digital content that has been released under a Creative Commons License – these licenses make it very clear as to how you may re-use the content.
For example:
By Adam Ognisty (Own work) [CC-BY-3.0], via Wikimedia Commons
This image is licensed under a Creative Commons license
So always keep an eye out for the Creative Commons logos when using digital media created by others that is available from online sources
For more information on Creative Commons licenses visit:
http://creativecommons.org/
Information about copyright can be found at: https://libguides.library.dmu.ac.uk/copyrightGDPR
If you have any questions or concerns about the copyright status of any materials that you are wishing to use to support teaching and learning, you should contact the DMU copyright Officer, see: https://libguides.library.dmu.ac.uk/copyrightGDPR