When I use an image, I also describe the image in the alternative text for those who are visually impaired.
It is important to make sure your materials are accessible in the online environment for all students, including those with disabilities. Describing images and their relation to the written or accompanying information ensures that all students benefit from and can understand the added value of the images.
Step by step
in Brightspace

Alternative text for images in Brightspace
Each time that you add an image in Brightspace you are prompted to fill in an alternative text. Make sure that the alternative text is a clear description of the image as well as its relation to accompanying material.
Also add alternative texts for decorative images so that students with a visual impairment can get a feel for the aesthetic of the page.