Force all thumbnails to be rectangle to a specified aspect ratio.
Thumbs are created rectangle to the center of the image using the aspect ratio specified in the advanced settings.
You must upgrade your G3 install to the latest version as of this writing. Verify by going to your modules page and see if Gallery core application is 41 or greater.
This module may be downloaded from the Gallery-contrib git repository here
Click the download button for the module you want. Extract the module to your gallery3/modules directory.
Activate the module: Login -> Admin -> Modules. Check the box next to the module.
Click update at the bottom of the page.
The default aspect ratio of the thumbs is 3:1. If you want to change this, login, click; Admin -> settings -> Advanced and change the rectangle_thumbs - aspect_ratio from 3:1 to a value you desire.
Similar module: Gallery3:Modules:square_thumbs