This theme component allows you to show topic thumbnails in topic list views. You can see a demo right here on meta by visiting the #theme category.
Optimized images are generated for the lists, and different resolutions are made available for high-dpi displays. Images are lazy-loaded as you scroll (where native browser support is available).
There are three modes, configurable per-category using the theme settings:
And list mode:
This component makes use of brand new APIs in Discourse core, so you need to be running the latest version of tests-passed for it to function correctly.