[Public] Understanding Page Orientation and Rotation in PDFs

 

When working with PDFs, it's often necessary to determine the orientation (portrait or landscape) of a page and whether the content is rotated. Our SDK provides two main approaches for this:

• PdfDocument.Pages[i].PageRotation – metadata-based rotation

• OcrInput.DetectPageOrientation() – OCR-based orientation detection

This article explains the difference between the two and how to use them effectively.

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Understanding Orientation vs. Rotation

• Page orientation refers to the page layout:

  • Portrait (height > width)

  • Landscape (width > height)

• Rotation angle refers to how the content on the page is rotated relative to the natural reading direction (e.g., 90°, 180°, etc.)

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Using IronPdf.PdfDocument.PageRotation

 

IronPDF returns the PageRotation value by reading the rotation metadata that is embedded in the PDF file. It tells you how the content is programmatically rotated, which is reliable and consistent if the PDF is well-formed.

Example

 

 

This approach gives you both:

• Page orientation (based on width/height)

• Rotation angle (from PDF metadata)

Best for: Structured PDFs with consistent metadata

 

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Using OcrInput.DetectPageOrientation()

 

IronOCR detects orientation of a PDF page by analyzing the visual layout of each page using OCR and infers the likely reading direction. It does not rely on metadata.

Example

 

 

This is useful for:

• Scanned documents

• Image-based PDFs

• Files without proper metadata

Note: The accuracy depends heavily on text density and clarity. Sparse or misaligned text may cause incorrect detection. To avoid this, use Rectangle and do OCR on area that have denser text to avoid wrong orientation returned.

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Recommendation

• Use PdfDocument.PageRotation when working with digital PDFs that have correct metadata.

• Use OcrInput.DetectPageOrientation() for scanned or image-based PDFs where metadata is missing or unreliable.

• For best results, consider using both methods and applying custom logic to resolve discrepancies in critical workflows.

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Summary

If you're seeing inconsistent rotation results, we recommend checking the specific page layout and using both methods together for validation.