Fast Summary: Straightening Crooked Scans
When scanning batches of receipts, legal filings, or book pages through a sheet-fed scanner or smartphone camera, pages frequently feed at a 2° to 8° diagonal tilt.
Beyond looking messy, skewed pages severely degrade OCR accuracy because optical recognition engines expect horizontal text baselines.
Use the Deskew PDF Tool on Tools24Now to automatically detect baseline angles and straighten crooked pages across your entire document.
How Computer Vision Deskewing Works
The deskew algorithm runs a discrete 3-step image analysis pipeline directly inside your browser:
- Binarization & Edge Detection: Converts the page into a high-contrast binary map, separating dark ink glyphs from paper background grain.
- Hough Line Transform & Projection Profile: Measures the angle of horizontal text lines across paragraphs to determine the exact tilt angle (e.g.,
-3.45°). - Bilinear Affine Transformation: Rotates the image canvas in reverse by that precise angle, padding borders with clean white margins.
Step-by-Step Straightening Guide
- Go to the Deskew PDF Tool.
- Upload your crooked or tilted PDF document.
- The automatic scanner calculates tilt deviations across all pages.
- Click Straighten All Pages.
- Download your perfectly aligned, professional PDF.