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How to Detect Page Rotation

Chaknith Bin

Updated:August 31, 2025

Determining page rotation involves identifying the degree of rotation applied to a page within a document. This process specifically determines if the page has been rotated clockwise or counterclockwise by angles of 0, 90, 180, and 270 degrees. This information is crucial for rendering or processing the document accurately, ensuring that pages are displayed or printed in their correct orientations.

IronOCR takes page rotation detection to the next level. Once rotation has been detected, the returned value can be used in combination with the Rotate method to adjust the image to the correct orientation.

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Detect Page Rotation Example

After loading the document, you can utilize the DetectPageOrientation method to identify the rotation of each page. This method supports degrees of 0, 90, 180, and 270. For skewed images, the Deskew image correction method can be used. Subsequently, rotate the image back to its original orientation using the degree returned from the function. Let's proceed with a sample PDF.

:path=/static-assets/ocr/content-code-examples/how-to/detect-page-rotation-detect-page-rotation.cs

using IronOcr;
using System;

using var input = new OcrInput();

// Load PDF document
input.LoadPdf("Clockwise90.pdf");

// Detect page rotation
var results = input.DetectPageOrientation();

// Ouput result
foreach(var result in results)
{
    Console.WriteLine(result.PageNumber);
    Console.WriteLine(result.HighConfidence);
    Console.WriteLine(result.RotationAngle);
}

Imports IronOcr
Imports System

Private input = New OcrInput()

' Load PDF document
input.LoadPdf("Clockwise90.pdf")

' Detect page rotation
Dim results = input.DetectPageOrientation()

' Ouput result
For Each result In results
	Console.WriteLine(result.PageNumber)
	Console.WriteLine(result.HighConfidence)
	Console.WriteLine(result.RotationAngle)
Next result

Understanding the Result

• PageNumber: Indicates the zero-based index of the page.
• RotationAngle: Provides the rotation angle in degrees. This angle can be used with the Rotate method to return the image to its upright orientation. For example, if an image is rotated 90 degrees clockwise, you would pass an angle of 270 (calculated as 360 - 90) to the Rotate method to straighten it.
• HighConfidence: Indicates the level of confidence in the orientation result, which helps in handling edge cases more effectively.

Advanced Detect Page Rotation

The DetectPageOrientation method also allows you to provide an optional parameter that controls the level of detail in the detection. By providing OreitnationDetectioMode enums as a parameter, users can customize and adjust the detecting speed and details based on their needs.

Here's a quick code example on how to use it.

:path=/static-assets/ocr/content-code-examples/how-to/detect-page-rotation-detect-page-rotation-advanced.cs

using IronOcr;
using System;

using var input = new OcrInput();

// Load PDF document
input.LoadPdf("Clockwise90.pdf");

// Detect page rotation with Fast mode
var results = input.DetectPageOrientation(OrientationDetectionMode.Fast);

// Ouput result
foreach(var result in results)
{
    Console.WriteLine(result.PageNumber);
    Console.WriteLine(result.HighConfidence);
    Console.WriteLine(result.RotationAngle);
}

IRON VB CONVERTER ERROR developers@ironsoftware.com

There are currently four speed options available for OrientationDetectionMode:

• Fast: The Fast orientation mode detects the orientation angle at high speed but with low accuracy; as such, it is more ideal for draft or bulk processing where speed is crucial. This is the default setting for the DetectPageOrientation method.

• Balanced: The Balanced orientation mode determines the orientation angle with balanced speed and accuracy; it is generally more suited for default or production tasks.

• Detailed: The Detailed orientation mode determines the orientation angle with low speed but high accuracy; as such, it is generally more suited for precise or critical tasks.

• ExtremeDetailed: The ExtremeDetailed orientation mode determines the orientation angle with the slowest speed but provides the highest accuracy possible. However, the slower speed compared to other options makes it ideal only when the Detailed option isn't sufficient or the text input itself is heavily skewed and distorted.

Chaknith Bin

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Software Engineer

Chaknith works on IronXL and IronBarcode. He has deep expertise in C# and .NET, helping improve the software and support customers. His insights from user interactions contribute to better products, documentation, and overall experience.

Reviewed by

Jeffrey T. Fritz

Principal Program Manager - .NET Community Team

Jeff is also a Principal Program Manager for the .NET and Visual Studio teams. He is the executive producer of the .NET Conf virtual conference series and hosts 'Fritz and Friends' a live stream for developers that airs twice weekly where he talks tech and writes code together with viewers. Jeff writes workshops, presentations, and plans content for the largest Microsoft developer events including Microsoft Build, Microsoft Ignite, .NET Conf, and the Microsoft MVP Summit