[jsjohnst]

Tumblr did something similar, but only for exact matches. You can tell if it’s a legacy image or not by looking for a hash in the image url path.

Legacy style: https://66.media.tumblr.com/tumblr_m61cvzNYF81qg0jdoo1_640.g...

New style: https://66.media.tumblr.com/76451d8fee12cd3c5971e20bb8e236e3...