I implemented something similar when I was playing around on a personal page. It's built by Jekyll and inlines a base64 version of the jpeg with a CSS blur filt

I implemented something similar when I was playing around on a personal page. It's built by Jekyll and inlines a base64 version of the jpeg with a CSS blur filter, then lazyloads the real image and transitions it in via opacity 0->1. You can see it in action here: https://www.road-beers.com/ https://www.road-beers.com/