Smart Scan Repair
Drag four corner handles to the edges of your document, then export a flat, perspective-corrected image or PDF — entirely in your browser.
Drop files here, browse
Drop a document photo or a scanned PDF — contract, receipt, whiteboard, or printed page
Max file size: 100 MB
Perspective Correction
Drag the four corner handles to match the document edges. The warp engine computes an inverse homography and resamples every pixel with bilinear interpolation.
PDF Input Support
Drop a scanned PDF or image-based PDF and the first page is rendered to a high-resolution canvas ready for corner editing. Export the result back as a PDF.
Private by Design
Your file never leaves your device. All rendering and processing runs in Web Workers inside your browser — no server, no account, no data collection.
Fix crooked document photos and scanned PDFs in your browser
When you photograph a contract, receipt, whiteboard, or printed page, the camera angle often introduces perspective distortion — parallel edges converge and the document looks trapezoidal instead of rectangular. Smart Scan Repair corrects that entirely in your browser. It also accepts PDF files: drop in a scanned or image-based PDF and the first page is rendered into a high-resolution canvas for editing. Drag the four corner handles to the document edges, choose an output size, and click Repair Document. The result is a flat, perspective-corrected image ready for archiving, sharing, or OCR.
How it works
For image files, the tool reads EXIF orientation data and corrects rotation automatically. For PDF files, PDF.js renders the first page at ~300 DPI — no server involved. Once your file is loaded, a warp engine calculates a perspective transform from the four corner positions and resamples every pixel using bilinear interpolation. All heavy computation runs in a background Web Worker, keeping the UI responsive even for large files.
Output size guide
Auto (from corners) estimates the output dimensions from the average edge lengths of your selection — the best choice for photos. A4 portrait (2480 × 3508 px) matches an A4 page at 300 dpi, ideal for international documents. US Letter (2550 × 3300 px) targets North American paper at 300 dpi. Original size outputs at the same pixel dimensions as the source file.
Privacy — your files stay on your device
Your file is processed entirely inside your browser using the Canvas API, PDF.js, and a Web Worker. Nothing is sent to any server. ConvertForge does not collect, store, or analyse your files. You can even use the tool offline once the page has loaded.
Frequently Asked Questions
Is Smart Scan Repair just a crop tool?
No. A normal crop tool only cuts away unwanted edges. Smart Scan Repair uses four-corner perspective correction: you mark the actual corners of an angled or trapezoid-shaped document, and the tool flattens that selection into a straight rectangular page before export.
What file formats does it accept?
JPG, PNG, WebP images, and PDF files. JPEG EXIF orientation is automatically corrected so portrait photos appear right-side up. PDF pages are rendered at approximately 300 DPI before editing.
Does it support multi-page PDFs?
The current version repairs the first page of a PDF. Multi-page support is planned for a future update. When you drop a multi-page PDF, a notice is shown at the top of the editor.
What happens if the PDF is password-protected?
Password-protected PDFs cannot be rendered. You will see an error advising you to use the Unlock PDF tool first to remove the password, then try Smart Scan Repair again.
Is there a file size limit?
The tool accepts files up to 100 MB. Images larger than 8,000 px on either side are automatically downscaled before editing. PDF pages are rendered within the same limit.
What does "Auto" output size mean?
The tool estimates output dimensions from the lengths of the edges you marked with the corner handles — roughly how wide and tall the document appears. The result is capped at 4,096 px on the longer side.
Can I export directly to PDF?
Yes. Choosing PDF creates an A4-sized PDF with the corrected image centred and scaled to fit. The PDF is generated entirely in your browser using pdf-lib — no uploads.
Why does the result look blurry at the edges?
Perspective correction stretches the far corners of the image. The further a corner handle is from the centre, the more that area is stretched and the lower its effective resolution. Placing handles precisely at the document corners gives the best quality.