Summary
As a rule of thumb, only upload JPG images to your posts and avoid PNGs.
PNG images can be smaller than JPG in certain contexts, but mostly not. So, to make it easy, let’s convert all PNGs to JPG before uploading them into the event.
A free, online tool exists here: https://png2jpg.com/. Of course, Photoshop and other image editing apps can do this conversion, also.
Why is this important?
WordPress creates several versions of the image you upload. Some version of this image ends up syndicated in many places (e.g., The Libraries home page). Therefore, we can end up with a PNG thumbnail that is 4-5 times the size it should be for very little aesthetic gain. This makes a big difference when that thumbnail is loaded thousands of times on our home page.
If you have any questions, please contact lib-webmaster@uiowa.edu.