The PDF scan deskew tool detects small skew angles in scanned PDFs, contracts, invoices, and phone-captured documents directly in your browser, then exports a new straightened PDF. It is useful when scanner feeding, camera capture, or document handling leaves pages slightly tilted.
Key Features
- Process all pages or a selected page range.
- Detect small skew angles from ±1° to ±20°, with ±6° as the default.
- Use coarse and fine angle search for more stable detection.
- Adjust gray threshold, ignored edge ratio, minimum apply angle, and minimum confidence.
- Choose JPG or PNG page reconstruction and set output render scale.
- Copy unselected pages into the output PDF.
- Process files locally in the browser without uploading documents.
How To Use
- Upload a PDF file or drop it onto the upload area.
- Enter a page range if needed, or leave it empty to process every page.
- Adjust max angle, search steps, and confidence settings for your scan quality.
- Click Start Deskew, wait for processing, and download the new PDF.
Parameter Tips
- For ordinary scans, keep max angle at ±6°, coarse step at 1°, and fine step at 0.2°.
- For more visibly tilted pages, raise the max detection angle to 10° or 15°.
- If page borders include dark shadows or binding marks, increase the ignored edge ratio.
- If false positives appear, raise minimum confidence. If too many pages are skipped, lower it slightly.
- JPG creates smaller files, while PNG better preserves text and line art.
Notes
- Corrected pages are rebuilt as image pages, so text layers, vector objects, and selectable text may not be preserved on those pages.
- This tool is for small-angle deskewing, not for fixing 90° or 180° page orientation errors.
- Encrypted PDFs cannot be processed directly and must be unlocked first.
Privacy
PDF files are read, rendered, detected, corrected, and exported in the current browser. The tool does not upload document content to a server.