Face swap on a photo

Face swap is one of the most common tasks people come to neural networks for: put your face into another look, neatly change a face in a group shot, try on a photoshoot that never happened. Technically it's a long-solved task you can do in a minute. But doing it so the result doesn't give away the fake — and staying within decency — is worth discussing separately.

How it works

The network takes a face from one image (the source) and transfers it to another (the target), while preserving the target's lighting, angle and expression. The key word is preserving: a good result isn't "cut and paste" but a rebuild in which someone else's face naturally fits the new light and angle. So quality depends a lot on how similar the two source shots are in angle and lighting.

Upload two photos — a face and a scene to place it into. See the result right here.

To make it convincing

• A similar angle. A front-facing face sits poorly on a profile. Take a source at the same angle as the target.
• Similar light. If the scene is lit from the left and the face was shot lit from the right, the viewer's brain feels the fake immediately. Many services adjust lighting automatically, but it's better to pick close sources.
• Good quality of the source face. The sharper and larger the source face, the more detail transfers.
• Finishing. After a swap it's often worth lightly improving the final photo — matching the sharpness and colour of the face to the rest of the frame.

Where it's really needed

• Put yourself into a look for an avatar, cosplay, concept art.
• Replace a face on a ready stock scene to get "your" photo without a shoot.
• Fix a group photo where someone blinked in the otherwise good shot — by substituting their face from another take.
• Anonymization in reverse: replace a person's face with a synthetic one so as not to show the real one.

Important: ethics and the law

This chapter can't end without an honest talk. Face swap is a powerful tool, and it has a dark side: deepfakes, doctored photos, using someone's face without consent. Simple guideposts:

• Someone else's face — only with that person's consent. Especially if the result will be published.
• Don't pass a fake off as reality where it misleads — from "evidence" to kompromat. In many countries this can carry legal liability.
• Don't use it for intimate or degrading images — it's both illegal and beyond the pale.

The tool is neutral; responsibility lies with whoever uses it. A healthy rule: do only what you'd be willing to show to the person whose face you're using.

What's next

Face swaps are often done on old or low-quality photos — in which case the next logical step is to raise the quality of the whole shot.

In the Twelver chat you can upload a photo right into the conversation and ask to swap the face — no separate apps. A few operations are free after signing up.