Image sizes can be set when you first add the image in your page. The size can also be changes by right click on the image-> image properties.
Here is the example of the image sizes:
|Image Type||Size (width by height)
||Page Using Image Type|
|Banner Image||Preferred Width 1920 pixels|
|Center Column Image||Max Width 434 pixels||Residence Life|
|Right Column Image||Preferred Width 276 pixels||Academic Subpages|