reverse image search: how people get found from a photo

a photo can identify you in a few specific ways. knowing which is which tells you what's worth doing and what's theatre.

the three routes

• matching the same image. a search engine finds other copies of that exact picture. this is what catches someone who reused a photo from a public profile. it only works if that picture already exists somewhere a crawler has seen.
• matching the face. separate, and much stronger: it finds different pictures of the same person. this is what people mean when they worry about being recognised.
• reading the background. no technology needed. a street name, a view, a distinctive building, a piece of post, a reflection. in practice this identifies more people than either of the above.

what actually helps

• don't reuse photos across accounts. this is the single most effective thing on the page. a picture that exists in exactly one place cannot be matched to another place. reusing a photo from a public profile is how most people are actually linked.
• keep your face out of it, or crop so a face match has nothing to work with. that takes route two away. a face isn't the only thing that matches, though -- cover distinctive tattoos, scars and jewellery too.
• check the background before the subject. five seconds. it defeats route three, the one that needs no tools and no skill.
• share with fewer people. unglamorous, and it dominates everything else. a picture five people have is a different risk from one five thousand people have, no matter what's in it.

what doesn't help much

• light blurring or pixelation of a face. it can sometimes be undone. even when it can't, enough shape often remains to narrow a search. crop instead or paint over it with no transparency.
• watermarks. they discourage casual reposting. they do nothing against matching.
• flipping or slightly cropping to beat a match. it defeats naive comparison and not much else.
• stripping metadata — worth doing, but for a different threat. it's covered in how to remove exif and gps data from your photos and it has no effect on any of the three routes above.

how sissy-haven handles this

route one only works if a picture sits somewhere a crawler can reach. no post here does. there are no public profiles, no feed anyone can browse, no follower lists, and nothing anyone uploads is indexed by a search engine. the only pages a crawler can see are ones like this guide. a post goes to a small audience the app picks, and to no one else.

routes two and three are yours. what's in the frame is your decision, and the notes above are the ones worth taking. we'd rather say that than imply the app covers it. the checklist for sharing a photo safely is the practical version of both.

and if route one is the one that worries you, the fix is structural rather than technical: fewer copies, in fewer places. that is what this app is for.