How to Detect Page Rotation

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

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.