Are two photos the same person? What a comparison can and cannot tell you

Why there is no face match here

Deciding that two faces are the same person is face recognition. It needs a model trained on large collections of faces, it makes mistakes that fall unevenly across ages, skin tones and lighting, and a confident-looking score from a website can do real harm when someone relies on it — to accuse, to verify an identity, or to track a person. A tool that compares pixels is the wrong instrument for that question, so this site does not attempt it.

What the site's visual similarity model measures is how alike two pictures look overall — the scene, the colours, the composition. Two photos of different people against the same wall can score higher than two photos of one person in different places. That is why its label is “visual content similarity” and never “same person”.

What a comparison can honestly show

Whether one photo is an edited or cropped copy of the other: the similarity view reads structural similarity and perceptual hashes, and the alignment note says if one is a scaled or shifted copy. Whether the files are byte-identical: the metadata view compares SHA-256 hashes, camera fields and dates. And where two copies differ: the difference view marks retouched areas as numbered regions.

If you need an identity check

Identity questions belong to the people and services responsible for them — an employer's verification process, a bank, a platform's reporting channel, or the police. None of them should rely on a similarity score from a comparison tool, this one included.