Glossary / PDF Watermark

What Is a PDF Watermark?

A PDF watermark is text or an image overlaid on one or more pages of a PDF document to indicate status, ownership, or confidentiality. Common examples include "DRAFT," "CONFIDENTIAL," company logos, and copyright notices. Watermarks are typically semi-transparent so the underlying content remains readable.

Types of watermarks

Text watermarks stamp words or phrases across pages, often at a diagonal angle. Image watermarks overlay a logo, seal, or graphic. Both can be placed in the foreground (on top of content) or background (behind content), depending on whether visibility or subtlety is preferred.

How watermarks are implemented

In the PDF format, watermarks are added by modifying the page's content stream. Text watermarks use PDF text operators with a transparency (alpha) setting, while image watermarks embed the graphic as an XObject. Because watermarks are part of the page content, they appear when the PDF is printed or viewed on any device.

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