How can I mark scanned photos to show authorship and survive light editing?

A common first step is to add authorship metadata such as the Author and Copyright fields in your photo software. If exported properly, that information can travel with the JPEG. However, metadata is easy to remove or change, so it’s best for identification rather than protection.

A visible watermark is another option, but it can distract from the image and can often be cropped or edited out.

If you want something more likely to survive light edits, invisible digital watermarking is the stronger approach mentioned in the answers. Services like Digimarc are designed for this and can persist through some basic processing better than plain metadata. They’re also more useful if you ever need to demonstrate authorship later.

So, in practice: use metadata as the standard baseline, add a visible watermark only if you accept the visual tradeoff, and consider invisible watermarking if survivability matters more.