Background Pony #55F8
Per the search help page:
It wouldn’t find images that have been deleted, though, AFAIK.
orig_sha512_hash:
for the exact source filesha512_hash:
for images after optimization by the site, eg. removing embedded thumbnails and metadataIt wouldn’t find images that have been deleted, though, AFAIK.
The first image was >>311260 (deleted), by Braeburned as you thought, but deleted due to DNP. Of course, you might know about other sites with less respect for copyright.
I didn’t find anything for the second one. There’s not a lot to go on, so unless you recognize the artist or character, that’s a long shot.