Try it for real.
This is the exact process our users go through, on photos nobody has marked yet. Pick one, we mark a copy with your name in front of you, take it anywhere you like, bring it back, and watch your name come out of the pixels. Or try to make sure it doesn’t.
Keep the picture recognisably the same, but make the mark unreadable. Each scan shows both: how much of the original is left, and what the scanner found.
Similarity is how much of the original is still present and matching in your version, 0–100.
Images you upload here are read once and discarded. The lab keeps only the verdict and the similarity. Your marked copy is deleted after two days.
A few marked copies a day and a few scans a minute per connection, so the lab stays fast for everyone.
The only thing that does not carry the mark is a new image: a scene redrawn from scratch rather than copied. Then you no longer have the photo you wanted; you have a different picture that merely resembles it, and the lab still recognises where it came from.
This is exactly what your own photos would get.
Every photo you mark with dipmark behaves like these, in your own registry, with your own recipients, and a log of every sighting.