Lookup

A lookup reverse-searches one of your images against external sources to backfill its tags and sources: “where does this picture come from, and what do other people tag it?”.

monbooru itself never goes online. Every lookup runs through a paired monloader instance, so set one up and pair it first - see Pairing. The actions below stay hidden until the pairing is live. How the lookup chain itself works (which services are asked, in which order, similarity floors) is documented on the monloader lookup page.

What a lookup searches

Two backends, together or alone depending on what monloader has enabled:

  • Online boorus and similarity services: matches the file by its md5 hash on booru sites, and by image similarity through IQDB and SauceNAO. A booru hit records a new source on the image and merges in its tags.
  • Hydrus Public Tag Repository (PTR): matches the file by its sha256 against monloader’s local PTR index. Only available when monloader has the PTR enabled. Pulls the matched post’s tags.

Boorus index the original file’s hash, so a resized or re-encoded copy usually misses on hash and only turns up similarity candidates. A miss reports what was searched along with the file’s hashes; a similarity candidate carries a ~NN% match score.

Running lookups from monbooru

  • Detail page, Lookup. Offered in the tag editor whenever a monloader is paired. With the PTR enabled the button opens a small dialog to pick both, PTR only or online boorus; without it the online lookup runs straight away. A found post’s tags are merged in and a booru match is recorded as a source.
  • Detail page, source refresh. Each source row with a URL has a refresh action that re-pulls that post’s tags, commentary and notes. A ptr source has no URL and refreshes by sha256; a similarity-matched source (~NN%) skips the usual same-file check.
  • Batch lookup. The gallery’s Actions chooser and the selection batch bar run a lookup across the whole scope: either refresh tags from each image’s primary source, or run the hash and similarity lookup per image. With the PTR enabled the hash mode can be narrowed to PTR only or online boorus only, so a large batch can stay on the free local index or spare the online services.
  • Tags page, PTR lookup. Pulls a tag’s known aliases and implications from the PTR into your catalog, per row or for the whole current search. See Tags.

A booru post that names a parent post links the two as a derivative relation once both are in the gallery - see Relations.