# Auto-crop & de-warp — flatten a photographed page, no upload

> Detect page corners and flatten perspective so a photographed document looks like a flatbed scan. Adjust corners by hand any time — in your browser, no upload.

Detect the page corners in a photo and flatten the perspective so a document shot at an angle looks like it came off a flatbed scanner. You can nudge the corners by hand whenever the auto-detect isn't perfect — all in your browser.

The difference between a photo of a document and a scan of one is geometry: a scan is flat and rectangular, a photo is tilted and keystoned. Auto-crop finds the page in the frame and de-warp corrects the perspective, turning the snapshot into something that reads and prints like a real scan.

Automatic detection handles clean cases; the manual corner handles are there for the rest — a page on a busy desk, or one that blends into its background.

After cropping, straighten small tilts with Deskew, boost legibility with Scan filters, and assemble the result with Build PDF.

## How to

1. **Add a page.** Use a camera scan or an imported photo.
2. **Auto-detect corners.** The page boundary is found automatically.
3. **Adjust.** Drag any corner to fix the detected edges.
4. **De-warp.** The perspective is flattened into a clean rectangular page.

## FAQ

### What does de-warping actually do?

It applies a perspective transform that maps the four page corners to a rectangle, removing the keystoning you get when a photo is taken at an angle.

### What if the corners are detected wrong?

Just drag them. Auto-detection gives a starting point; manual corner adjustment lets you get it exact even on low-contrast or cluttered backgrounds.

### Will it crop out my content?

No — it crops to the page you set, keeping everything inside the corners. Widen the corners if part of the page falls outside the detected box.

### Is the image uploaded to process it?

No. Corner detection and the perspective transform run on a canvas in your browser, so the page image stays local.


## Related tools

- [Deskew](https://www.safepaper.app/scan/deskew)
- [Scan filters](https://www.safepaper.app/scan/filters)
- [Build PDF](https://www.safepaper.app/scan/to-pdf)
- [Camera scan](https://www.safepaper.app/scan/camera)

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Markdown: https://www.safepaper.app/scan/auto-crop.md

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