The BY - Attribution element of every Creative Commons license requires you to add an attribution statement for the image to your work. This is best placed directly under the image, whether on a poster or in a PowerPoint.
Creative Commons suggests using TASL
Here's an example of what TASL looks like in action for this image:
Programming Code by Martin Vorel CC-BY-SA 4.0
Finding all the pieces of your attribution may take a little hunting. If you need help, ask your librarian.
Attributing the source properly is extremely important. If the CC license is version 2.0 or earlier, you may be sued for not having a proper attribution using the above TASL standards. For 3.0 and newer licenses you will have 30 days to fix the attribution before you'd get sued for misuse of the licensed material.
If you make any of the following changes to an image, it is considered an adaptation:
Changing the file format of something is NOT an adaptation and is allowed under all Creative Commons licenses, even NoDerivatives.
If the original work is licensed under ND NoDerivatives, you can only make adaptations privately. You may not share them with anyone. To use a work with a ND license, you cannot make any of the adaptations mentioned above.
If the original work has a SA ShareAlike license, you must license your new work with the same or compatible ShareAlike license if you make any adaptations. You need to determine license compatibility to determine if the licenses for the works you’re using can be combined and are compatible with the license you apply to your new work.
In the License Compatibility chart below, determine which license to apply to your adaptation by comparing the licenses on the left and top. If there’s a green check, you can combine them and you need to use the the most restrictive (furthest down or to the right) license of the licenses you are combining. If the licenses are not compatible (an X in the chart), you cannot combine them.
CC License Compatibility Chart by Kennisland. CCO