Annotation
PDF Annotation
A markup element added to a PDF page, such as highlights, comments, stamps, or drawing shapes.
Technical Detail
In the PDF specification (ISO 32000-2:2020), annotation is implemented as a specialized object within the document's object graph. PDF files use a cross-reference table to index every object by byte offset, enabling random access without sequential parsing. This architecture allows annotation to be read, modified, or extracted independently of other document elements. The binary structure supports incremental saves, where changes append to the file without rewriting existing content.
Example
```javascript
// Add text watermark to PDF pages
const pages = pdf.getPages();
for (const page of pages) {
page.drawText('CONFIDENTIAL', {
x: page.getWidth() / 2 - 100,
y: page.getHeight() / 2,
size: 48,
opacity: 0.2,
rotate: degrees(45),
});
}
```
Related Formats
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M
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S
Split PDF
C
Compress PDF
R
Rotate PDF
A
Add Page Numbers
P
PDF to JPG
W
Watermark PDF
R
Reorder PDF Pages
F
Flatten PDF
E
Edit PDF Metadata
S
Sign PDF
J
JPG to PDF
E
Extract Text from PDF
D
Delete PDF Pages
R
Reverse PDF
E
Extract PDF Pages
E
Extract Odd/Even Pages
R
Resize PDF Pages
C
Crop PDF
I
Insert Blank Pages
D
Duplicate PDF Pages
P
PDF to PNG
A
Add Header & Footer
A
Add Text to PDF
A
Add Image to PDF
Related Terms
AcroForm
Bates Numbering
Bookmark
Color Management (PDF)
Content Stream
Cross-Reference Table
Digital Signature
Document Catalog
Encryption
Flattening
Font Embedding
Form Field
Incremental Save
Linearization
OCR
Page Tree
PDF
PDF/A
PDF/E
PDF Layers
PDF Optimizer
PDF Portfolio
PDF Redaction
PDF Signature
PDF/UA
PDF/VT
PDF/X
Redaction
Tagged PDF
Watermark
XFA