Sets view with default square aspect ratio.
Pages - Changing the aspect ratio for set cover images
By default many types of gallery page use square aspect ratio images for the sets view.
To change this, you can update the image profile for the gallery set.
When updating the image profile make sure to change both the set and set @2x versions so that both people with standard and retina displays can see the new image type.
The two image profiles work together, so changing just one of them will cause the images to be sized incorrectly on your site.
After you are done your site should look like this.
Regenerating image version on large sets may take a long time, so it's best to try it out on a set with just a few images first. Once you've decided on your chosen aspect ratio and tested it, you can repeat the process on larger sets.
You can try different aspect ratios to give your site a different look:
Sets view with unchanged aspect ratio.
Sets view with 3:1 aspect ratio to create a banner style.