A missing watermark does not prove that an image was made by a human.
That sounds obvious, but it matters because watermarking is often discussed as though it permanently divides synthetic media from everything else. In practice, digital files are copied, resized, recompressed, screenshotted, exported, and converted between formats constantly. Some provenance signals survive those operations. Others do not.
The first distinction is between visible watermarks and embedded information.
A visible mark is part of the pixels: a logo, label, or pattern intentionally placed where a viewer can see it. Embedded provenance can instead live in metadata or a cryptographically signed manifest associated with the file. Systems such as the C2PA specification are designed to record information about an asset’s origin and editing history.
Neither approach is indestructible.
Ordinary processing can erase evidence
A screenshot creates a new file from what was displayed on the screen. The screenshot may visually reproduce the original image almost perfectly while omitting the original file’s metadata.
Exporting from an image editor can do something similar. A JPEG may be converted to PNG. A platform may resize the image and create its own copy. A messaging service may recompress it. Metadata can disappear even when nobody intended to hide anything.
Visible marks have different weaknesses. Cropping may remove a mark near an edge. Resizing can make a subtle mark unreadable. Heavy compression can interfere with invisible signal-based watermarks. A screenshot generally preserves a visible watermark because the pixels are copied, but it may destroy metadata attached to the original file.
This is one reason provenance systems increasingly discuss more than one recovery method. C2PA, for example, supports the idea of durable credentials that can use mechanisms such as content fingerprints or watermarks to reconnect altered media with provenance stored elsewhere.
Absence is weak evidence
Suppose an image arrives without any AI label or provenance metadata.
That tells you what is present in the file you received. It does not reliably tell you what was present three transformations earlier.
The image may have originated in a camera and lost metadata. It may have been generated by a model and lost metadata. It may have been edited by a person, processed by a platform, downloaded, and screenshotted several times.
The same problem exists in reverse. A surviving provenance credential can provide useful evidence about origin and editing history, but it does not make the depicted claim true. Authentic provenance and factual accuracy are separate questions.
Watermarks therefore work best as evidence that can survive a chain of handling, not as a magical binary test.
The internet is an enormous file-conversion machine. Any detection system that assumes media will remain in its pristine original container is going to meet reality very quickly.