In several places, b2evolution lets you select an "Image Size" a.k.a. "Thumbnail Size" for the images you display.
In the name of the sizes you will find the following:
- type :
- fit will preserve the image dimensions ratio and reduce the image to make it fit into the specified dimensions
- crop will crop exactly to the required dimensions
- crop-top will crop by using preferably the top of picture (where the faces tend to be, when cropping vertical pictures)
- width (or max height in case of "fit")
- height (or max height in case of "fit")
- quality (for JPEG compression)
- percent of blur effect
If you need to change or add sizes, see the _advanced.php file.