Why ChatGPT changes your face

It isn’t editing your photo

When you ask ChatGPT to change a picture, it doesn’t adjust the one you gave it. It studies your photo, then paints a new image that matches what it saw plus what you asked for. Every pixel in the result is freshly made, including every pixel of your face. Nothing is carried across untouched.

That’s why it can do things no ordinary editor can, like swapping a background or changing an outfit. It’s also why it can’t leave your face alone. To the model, a darker background and a new face are the same kind of job.

Why faces drift

The model paints faces from what it has learned about faces in general, from an enormous number of them. So every face it paints is pulled, slightly, toward that average. Many of the photos it learned from were retouched or filtered before they were ever posted, so the pull is toward smooth skin, even features and bright eyes.

On a stranger’s face you would never notice. On your own you might not either, because we’re forgiving about faces we know. It’s the people who know you who see it straight away.

We tried it on a street

To see it for ourselves, we gave one of OpenAI’s image models a photo of a Paris street and asked for one thing: make it warmer. It came back square, framed differently, with a sunset that hadn’t been there and the parked cars quietly redrawn.

What we gave it

“Make it warmer”

The sign, in our photo

The same sign, after

Look closer and it gets stranger. The shop sign still says Prestige, but in different lettering, and the phone number under it is no longer quite the same number. The balloon on the sign next door has turned into something else altogether.

It was a beautiful picture. It just wasn’t the photo. And if a model will quietly rebuild a parked car, it will rebuild a face.

Prompts help, a little

Asking it to keep your face exactly the same does make a difference. It tries harder, and the result is closer. But it’s still painting your face rather than keeping it, so close is the best it can do. Run the same request two or three times and watch the face shift slightly with each one. That’s the tell.

Use the right tool for the job

If you need something that has to be made up, like a new background, a person removed or a different outfit, ChatGPT is a good choice. Just compare the face with your original before you share it.

But most edits people want aren’t that. They want the photo they took, with better light: brighter, warmer, less grey, the background a little darker. That needs an editor that adjusts your photo rather than repainting it, and that kind of editor can’t change a face even if it tried.