AI watermark

A watermark was originally a mark that shows a banknote is real, like the pattern you see when you hold it up to the light. AI watermarks come in two kinds. One is a visible mark placed in a corner of an image. The other is invisible to the eye but can be read by a program, hidden in an image's pixels or in sound.

Another method is provenance information, which records in the file which tool made it and when. The two are often used together. But re-photographing a screen or editing the file can erase a mark, and many tools add no mark at all. So having no watermark does not mean something is real.

It is like the country-of-origin label on food packaging. If it is there, you can tell where the food came from, but some products have the label peeled off or never had one.

To help people tell fake video and photos apart, many countries are making laws that require AI-made content to be labeled. When a social network adds an "Made with AI" tag, it often judges by reading marks like these.