- Fill area
This is the default setting, all thumbnails will be the same size causing some sides to be cropped from larger images.
- Fit area
Use to always use the full image as thumbnail, thumbnails are resized to fit the thumbnail area and will never be cropped.
- Fit vertically
Good for portrait images, this makes sure the full height of the thumbnail is kept, the width will be changed to maintain aspect ratio.
- Fit horizontally
Good for landscape images, this makes sure the full width is shown, the height will be changed to maintain aspect ratio.