Watermarks communicate status; they do not enforce access
A watermark can identify ownership, review state, or distribution context. It does not encrypt the PDF, prevent extraction, or securely remove underlying content.
Balance visibility with document readability
Use enough opacity to survive normal viewing without obscuring important text or diagrams. A centered rotated mark can span varied layouts, while corner placement is less intrusive.
- Preview a dense page and a sparse page.
- Use transparent PNG logos when appropriate.
- Apply only to selected pages when the meaning is page-specific.
Content overlays can preserve text and vectors
Adding a PDF drawing instruction can keep existing page text and vector content intact, unlike rasterizing the complete page. Any edit can still invalidate an existing cryptographic signature.