Sometimes you have no control over the sizing of the images going in to a Gallery or Portfolio in Divi. If you are adding big volumes of supplied images there is a quick way to make these a standard size.
You can use the following code for the gallery, just adjust the height to the desired look.
/* GALLERY image heights EVEN */
.et_pb_gallery_grid .et_pb_gallery_image.landscape img
height: 170px !important;
.et_pb_gallery_grid .et_pb_gallery_image img
For the Portfolio I head to the Divi Booster plugin and under modules you can set the height and width.