Attributor, a site that helps publishers track down unauthorized copies of their content, has raised another $3.2 million in funding.

The San Mateo, Calif. company says it offers a sophisticated way to detect when text or photos have been copied, taking a “fingerprint” of a paragraph or image’s essential features, then scanning 35 billion Web pages to see where the content has been duplicated. Then it helps publishers contact the offending sites and make them link back to the original article, share their advertising revenue, or just take the content down altogether.

Attributor also announced some big customers today, namely the Magazine Publishers of America and the United Kingdom’s Periodical Publishers Association. The company already serves large news organizations including Reuters and The Associated Press.

The round brings Attributor’s total funding to $25.2 million. The money comes from previous backers Sigma Partners, JAFCO Ventures, and Selby Venture Partners.