KissPDF Automatic Deskew PDF Tool
Automatically straighten skewed text and crooked scanned PDF pages, then review or fine-tune each page before downloading.
Fix crooked scanned documents and pages that entered a scanner at a slight angle before reading, sharing, archiving, or running OCR.
A compact Leptonica WebAssembly detector analyzes rendered page previews on your device.
Straighten a scanned PDF in four steps.
Choose a scanned or slightly tilted PDF from your device.
Leptonica analyzes every page and reports the proposed correction.
Switch to Manual and adjust individual pages in 0.1 degree steps.
Create a separate straightened PDF without rasterizing ordinary page content.
Practical guide
Deskew PDF pages online to automatically straighten crooked or tilted scans. You can also correct each scanned PDF page manually, while ordinary text and vector graphics remain sharp and searchable.
Automatic mode renders a temporary preview of each page and uses Leptonica to measure how strongly the text lines tilt. A confident correction of at least 0.1 degrees is applied to that page; low-confidence results are flagged for manual review and left unchanged.
Manual mode starts with the accepted automatic corrections and lets you change each page between -15 and +15 degrees. Positive values rotate clockwise. Use the buttons for 0.1 degree adjustments, the slider for larger changes, or apply the current angle to every page.
Choose Only straighten strongly skewed pages when small corrections are unnecessary. This raises the automatic threshold from 0.1 to 0.7 degrees while retaining the same Leptonica confidence requirement.
Page images are used only for angle measurement and preview. The downloaded PDF embeds and rotates the original page content, so ordinary text and vector graphics remain sharp and searchable. Rebuilding pages does not preserve interactive annotations, fillable controls, or digital signatures.
Clear answers based on how this tool actually works.
Deskewing, also written de-skewing, measures and corrects a slight page tilt that usually occurs when paper enters a scanner at an angle.
KissPDF renders a local preview and uses Leptonica pixel-profile analysis to find the clockwise correction angle. Only sufficiently confident results are applied.
Yes. Switch to Manual, navigate between pages, and set a different angle for every page.
Pages with little text, photographs, diagrams, handwriting, or noisy backgrounds may not produce a reliable Leptonica confidence score, so automatic mode leaves them unchanged.
No intentional page rasterization is used in the downloaded PDF. Ordinary text and vector graphics are transformed as PDF content.
No. PDF rendering, Leptonica detection, manual previewing, and PDF rebuilding run in your browser.