[gillesjacobs]

axe312ger/SQIP[1] does this effectively in low-quality image loading relying on the before-mentioned fogleman/primitive library. I think OP's project would be great to add as a new entry to the SQIP demo site [2].

In the thumbnail demo, the LQIP-custom approach (simple resize to low-res jpg thumbail+optimize jpg) approach preserves the more salient features better and has compression on-par-or-better than SQIP with lower processing times. So in my opinion the simple extreme resize+jpgoptim is preferable for thumbnails.

Thumbnails are only small part of LQIP story though and I can imagine RH12503/Triangula having much nicer results for larger images than fogleman/primitive. OP should consider writing an axe312ger/sqip plugin.

1. https://github.com/axe312ger/sqip

2. https://axe312ger.github.io/sqip/