The WebP format, which is developed by Google is becoming ever more popular on the net these days. With many popular websites and web browsers adopting it. WebP offers a modern image format that “provides superior and lossy compression for images on th web”. Having played with the file format myself, I can confirm that using WebP can dramatically reduce the file size of images, while keeping almost the same level of detail as a source image as in the “PNG” format.
For those using the “Thunar” file manager in Linux - i’ve written a small script which adds a custom action to Thunar. It uses ffmpeg to convert large screen grab images to the size required for Lutris game banners images. For games that don’t have a banner, you can screenshot your own to your Pictures/ folder when the game is open, then convert the saved images for use as game banners with this script.