Deskew PDF — Straighten Scanned Pages Automatically

What Is Deskewing?

When you scan paper documents, the paper is rarely perfectly aligned on the scanner glass. This creates pages that are slightly tilted — sometimes just 1-3 degrees, but enough to make text look crooked and make OCR unreliable.

Deskewing automatically detects the tilt angle and rotates the page to be perfectly straight.

Why Deskew Matters

• Readability — even a 2-degree tilt makes text uncomfortable to read on screen
• OCR accuracy — text recognition engines work significantly better on straight text (up to 30% accuracy improvement)
• Professional appearance — crooked scans look unprofessional in business documents
• Auto-crop accuracy — auto-cropping works better on straight pages

How to Deskew Online

Step 1: Upload Your Scanned PDF

Open MyPDF's Deskew tool and upload your scanned PDF.

Step 2: Process

The tool automatically:

1. Analyzes each page for text line angles


2. Calculates the optimal rotation correction


3. Rotates the page to align text horizontally


4. Fills any exposed corners (from rotation) with white

Step 3: Download

Download the straightened PDF.

Before and After

A typical scanned document improvement:

Metric	Before Deskew	After Deskew
Text angle	1.5-3 degrees off	0 degrees (straight)
OCR accuracy	82-90%	95-99%
Readability	Uncomfortable	Natural
Auto-crop quality	Inaccurate boundaries	Clean crop

When to Deskew

• Before OCR — always deskew scanned documents before running OCR for best results
• Before auto-crop — straight pages produce better auto-crop boundaries
• After scanning — make it part of your scan-to-PDF workflow
• Batch processing — deskew an entire folder of scanned documents at once

Tips

1. Deskew before OCR, always — this single step can improve OCR accuracy by 10-30%
2. Check multi-column layouts — deskewing uses the dominant text direction; mixed layouts may need manual adjustment
3. Combine with other scan cleanup — deskew → auto-crop → OCR is the ideal workflow
4. High-resolution scans deskew better — 300 DPI gives the algorithm more data to detect angles

Frequently Asked Questions

Does deskewing work on non-scanned PDFs?

It can, but it's designed for scanned images. Digital PDFs are already straight — deskewing them has no effect.

Will deskewing reduce image quality?

Minimal quality loss — the rotation interpolation is sub-pixel accurate. At 300 DPI, the difference is imperceptible.

What if a page is rotated 90 degrees?

That's not skew — that's rotation. Use Rotate PDF to fix 90/180/270-degree rotations first, then deskew for fine alignment.

Related Tools

• OCR PDF — Make scanned text searchable after deskewing
• Auto Crop PDF — Remove margins after straightening
• Rotate PDF — Fix major rotation (90/180/270 degrees)
• Compress PDF — Reduce scanned PDF file size