Fix Image Orientation

IronOCR’s OcrInput includes built-in methods to adjust image orientation for optimal OCR accuracy:

• Rotate(double degrees): rotates the image clockwise by the given degrees; use negative values for counter-clockwise rotations
• Deskew(int maxDeskewAngle = 45): corrects skew up to a maximum angle (default 45°); returns true if correction was applied
• Scale(int percent, bool scaleCrop = true): resizes the image proportionally (e.g. 150 for 150%)

using IronOcr;
using System;

class OrientationCorrectionExample
{
    static void Main()
    {
        using var ocr = new IronTesseract();
        using var input = new OcrInput();

        // Load an input image
        input.AddImage("example.jpg");

        // Detect and log current orientation if needed:
        var orientations = input.DetectPageOrientation();
        foreach (var r in orientations)
        {
            Console.WriteLine($"Page {r.PageNumber}: rotated {r.RotationAngle}°, confidence: {r.HighConfidence}");
            if (!r.HighConfidence)
                Console.WriteLine("Warning: low confidence in orientation detection.");
        }

        // 1. Rotate by 90°
        input.Rotate(90);

        // 2. Deskew if necessary (default max 45°)
        bool didDeskew = input.Deskew();
        Console.WriteLine($"Deskew applied: {didDeskew}");

        // 3. Scale to 150%
        input.Scale(150);

        // (Optional) save filtered image for inspection
        input.SaveAsImages("processed_images");

        // OCR the final corrected image
        var result = ocr.Read(input);
        Console.WriteLine("OCR text:");
        Console.WriteLine(result.Text);
    }
}

using IronOcr;
using System;

class OrientationCorrectionExample
{
    static void Main()
    {
        using var ocr = new IronTesseract();
        using var input = new OcrInput();

        // Load an input image
        input.AddImage("example.jpg");

        // Detect and log current orientation if needed:
        var orientations = input.DetectPageOrientation();
        foreach (var r in orientations)
        {
            Console.WriteLine($"Page {r.PageNumber}: rotated {r.RotationAngle}°, confidence: {r.HighConfidence}");
            if (!r.HighConfidence)
                Console.WriteLine("Warning: low confidence in orientation detection.");
        }

        // 1. Rotate by 90°
        input.Rotate(90);

        // 2. Deskew if necessary (default max 45°)
        bool didDeskew = input.Deskew();
        Console.WriteLine($"Deskew applied: {didDeskew}");

        // 3. Scale to 150%
        input.Scale(150);

        // (Optional) save filtered image for inspection
        input.SaveAsImages("processed_images");

        // OCR the final corrected image
        var result = ocr.Read(input);
        Console.WriteLine("OCR text:");
        Console.WriteLine(result.Text);
    }
}

Imports IronOcr
Imports System

Friend Class OrientationCorrectionExample
	Shared Sub Main()
		Dim ocr = New IronTesseract()
		Dim input = New OcrInput()

		' Load an input image
		input.AddImage("example.jpg")

		' Detect and log current orientation if needed:
		Dim orientations = input.DetectPageOrientation()
		For Each r In orientations
			Console.WriteLine($"Page {r.PageNumber}: rotated {r.RotationAngle}°, confidence: {r.HighConfidence}")
			If Not r.HighConfidence Then
				Console.WriteLine("Warning: low confidence in orientation detection.")
			End If
		Next r

		' 1. Rotate by 90°
		input.Rotate(90)

		' 2. Deskew if necessary (default max 45°)
		Dim didDeskew As Boolean = input.Deskew()
		Console.WriteLine($"Deskew applied: {didDeskew}")

		' 3. Scale to 150%
		input.Scale(150)

		' (Optional) save filtered image for inspection
		input.SaveAsImages("processed_images")

		' OCR the final corrected image
		Dim result = ocr.Read(input)
		Console.WriteLine("OCR text:")
		Console.WriteLine(result.Text)
	End Sub
End Class

Explanation

• Loading the Image: AddImage("example.jpg") loads the input into OcrInput--similar to Image.open(...) in PIL.
• DetectPageOrientation(): returns orientation information per page, including RotationAngle and HighConfidence flags (useful before applying corrections)
• Rotation: Rotate(90) rotates the image clockwise by 90 degrees—matching PIL’s rotate(degrees, expand=True) behavior.
• Deskewing: Deskew() automatically straightens minor skew. Returns true if the image was corrected.
• Scaling: Scale(150) scales the image proportionally to 150% the original dimensions—similar to resizing in the provided Python PIL example.
• Optional Export: SaveAsImages("processed_images") exports filtered images for debugging or verification before OCR.
• OCR Execution: ocr.Read(input) uses the preprocessed OcrInput for text extraction.