Some pictures made or edited on an iPhone now carry a hidden tag that marks them as AI-touched. The tag is a watermark called SynthID, and it is live in iOS 27.2, according to MacRumors. You cannot see it, and the iPhone has no way to check for it.
What changed
Every image made with Image Playground now gets the watermark. Some photos edited with Apple Intelligence do too. In MacRumors' tests of the Photos app, images changed with Extend and Reframe had it. Clean Up, another Photos tool, seemed to depend on the size of the edit. Small edits got no watermark. Larger ones did.
SynthID was created by Google. It marks images at the pixel level instead of adding a note to the file's data. Google says it does not affect image quality and is meant to survive cropping, filters and compression. Apple, OpenAI and others use it. Apple announced plans for it in June.
What is not known yet
To check an image, you have to use the SynthID Detector website. The iPhone has no built-in option for it. The report does not say whether Apple plans to add one, or where the size cutoff for Clean Up edits falls.
The takeawaySome AI-made or AI-edited iPhone photos now carry an invisible tag, and only the SynthID Detector website can check for it.