Image Deskew
How to Deskew a Scanned Image Using Aspose.Imaging for .NET

How to Deskew a Scanned Image Using Aspose.Imaging for .NET

Scanned documents and photos often appear tilted or rotated due to imperfect scanning. Aspose.Imaging for .NET makes it easy to deskew any raster image in just a few lines of code, producing clean, readable results.

Real-World Problem

Crooked scans reduce readability and look unprofessional. Manual correction is tedious and imprecise—automation is better.

Solution Overview

Use Aspose.Imaging to detect and correct the skew angle automatically. Choose whether to resize the canvas or fill background areas after correction, and save to any common image format.

Prerequisites

  1. Visual Studio 2019 or later
  2. .NET 6.0 or later (or .NET Framework 4.6.2+)
  3. Aspose.Imaging for .NET from NuGet
  4. A scanned photo or document (JPEG, PNG, TIFF, etc.)
PM> Install-Package Aspose.Imaging

Step-by-Step Implementation

Step 1: Load Your Image as RasterImage 

using Aspose.Imaging;
using Aspose.Imaging.ImageOptions;

string inputPath = "./input/scan.jpg";
string outputPath = "./output/scan_deskewed.jpg";

using (var image = (RasterImage)Image.Load(inputPath))
{
    // Step 2: Deskew the image
    // false = keep size, fill background; true = resize canvas to fit
    image.NormalizeAngle(false, Color.White); // Or Color.Transparent, Color.LightGray

    // Step 3: Save the deskewed image
    image.Save(outputPath, new JpegOptions { Quality = 90 });
}

Step 4: Review and Adjust

Open the output image in any viewer. If edges are lost, try NormalizeAngle(true, Color.White) to expand the canvas.

Use Cases and Applications

  • Straightening scanned photos, forms, or receipts
  • Preparing images for OCR or archival
  • Cleaning up business document workflows

Common Challenges and Solutions

Some corners are filled with white/gray: This is normal for strong skew angles; choose background color to match your needs.

Image is cropped: Use resize: true to expand canvas if you need to preserve all content.

Poor correction quality: Ensure you’re loading as RasterImage, not just Image.

Best Practices

  • Always preview deskewed results before sharing or archiving
  • Batch-process scans for speed and consistency
  • Keep original scans as backup

FAQ

Q: Can I use PNG or TIFF for lossless results? A: Yes—change JpegOptions to PngOptions or TiffOptions in the Save method.

Q: Can I automate for a whole folder of scans? A: Absolutely—wrap the code in a loop for batch deskewing.

Q: What color should I use for background? A: Use Color.White for paper, Color.Transparent for graphics, or match your document’s background.

Conclusion

Deskewing with Aspose.Imaging for .NET is fast, reliable, and easy to automate. For more advanced image corrections, see the Aspose.Imaging for .NET API Reference .

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