Visible or invisible watermark: which should an artist use?

• A visible mark (your name or signature on the picture) is read by people. It tells a viewer whose work it is and makes a copy look less usable. Its weakness is that it can be cropped out, covered or retouched, and a heavy mark spoils the image you want people to enjoy.
• An invisible mark is read by software. It leaves the picture looking the same and can carry an identifier. Its weakness is that edits can destroy it. Nothing about it is visible to a person, so it does not deter anyone by itself.

In our tests (three synthetic images, one watermark strength) the mark stayed readable after lossless saving, JPEG at quality 85 and above, WEBP at 90, black and white, and contrast, hue and sepia changes. It was lost after any resize, any crop, rotation, mirroring, a brightness change, stronger compression and a screenshot-like copy. Real artwork may behave differently. The full table is in what an invisible watermark survives.

That matters because most copies on marketplaces are resized or cropped for a product. For those, the invisible mark is usually gone, so we do not rely on it: finding the copy is done by comparing how the images look, which recognised resized, recompressed, recoloured and cropped copies in our tests, and only part of the time the smallest and most heavily cropped ones.

• Images you want people to see and share (social posts, portfolio): a small visible signature in a corner you would not want to lose, or your name in the file name and caption. Keep the image at a moderate size.
• The original, high-resolution file: keep it private. Share it only with buyers or print partners you trust. An invisible mark on that file helps you check later whether an unedited copy came from it.
• Proof of authorship: neither mark proves you made the work. Your working files, dated posts and history do. See how to prove you made your artwork.

• It does not stop someone saving, copying or reselling your image.
• It does not stop AI training.
• It does not remove a copy for you. You still have to find it and report it.

More on AI in can you stop AI from training on your artwork, and on finding copies in three ways to find copies of your artwork.

You register an artwork, we embed the invisible mark in the protected copy you download, and we check public web pages on a schedule for possible matches. We only see pages a search engine has indexed, a match is a possible match and never proof, and you decide what to do. We do not contact anyone for you. See the plans.