Stretch vs. Cropp preview image

I am creating a content-popup gallery with Huge-It (which I bought a few years ago).
However, I’ve looked for hours and still can’t find how to make the preview images look like their demo https://huge-it.com/wordpress-photo-gallery-demo-1-gallerycontent-popup/#close

Notice how the images are fitted into the box by either being cropped (if they are too wide, the sides are cropped, like in Impression of Sunrise, the first image), or displayed with spaces on the side from the edges of the block (Like the third image on the first row… Picasso’s).

I can’t find the option to create that kind of setup on my gallery. Instead, all the images are being stretched to fit a specific fixed size. Any help would be appreciated.