An image gallery can be easily built by using LightBox and Image Gallery scripts in Jekyll.
Lightbox is a solution that loads your image links, your Youtube links and your Vimeo links automatically in a minimalistic and responsive pseudo window/overlay. No adjustment to your links is required, just follow the instructions to install the css and js script.
The script Image Gallery creates an image gallery. The script reads all images from a specific (user-defined) folder in Jekyll, automagically crops them to 300px squares, using an image resize proxy service and shows them in rows of five. Just follow the very easy instrutions to install it and we are good to go.