Watermarks in PDF

Groupdocs.Watermark which is part of Conholdate.Total for .NET, can add watermarks in PDF documents by choosing one of the following ways.

XObjects

When Add method of Watermarker class is called, simple XObject is added to a PDF document.

Image XObject and Form XObject are used by GroupDocs.Watermark API to add ImageWatermark and TextWatermark respectively. XObjects are considered as a page real content, therefore, they are not removed by Adobe Acrobat during document sanitization.

Artifacts

The watermark can be represented by an artifact in a PDF document. The following example shows how artifact watermark can be added to a document with GroupDocs.Watermark using PdfArtifactWatermarkOptions.

AdvancedUsage.AddingWatermarks.AddWatermarksToPdf.PdfAddArtifactWatermark

Annotations

PDF Reference 1.7 An annotation associates an object such as a note, sound, or movie with a location on a page of a PDF document, or provides a way to interact with the user by means of the mouse and keyboard. PDF includes a wide variety of standard annotation types. A watermark annotation (PDF 1.6) is used to represent graphics that are expected to be printed at a fixed size and position on a page, regardless of the dimensions of the printed page.

Annotation is the third type of PDF entities by which a watermark can be represented. Use the following code snippet to add watermark annotation to a PDF document using PdfAnnotationWatermarkOptions.

AdvancedUsage.AddingWatermarks.AddWatermarksToPdf.PdfAddAnnotationWatermark

Print-only annotations

You can also add print only annotation watermark to the document setting PrintOnly property of PdfAnnotationWatermarkOptions. The following code demonstrates this approach.

AdvancedUsage.AddingWatermarks.AddWatermarksToPdf.PdfAddPrintOnlyAnnotationWatermark

For more details please visit this article.

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