How does a direct url to an image hosted on Tumblr load a page with the image embedded instead?

Lately, a direct url for an image (i.e., https://64.media.tumblr.com/....jpg) hosted on tumblr will load a page with the image embedded in it, rather than linking directly to the image. I'm wondering if anybody can help shed some light on how this works? Maybe it's a redirect? I'd like to see if there's a way to stop this from happening client-side.