Scan to PDF

Your phone camera as a document scanner: edge detection, perspective correction and a straight PDF, all in the browser with nothing to install.

Open in PDF ARENA

Scan with your phone

Nothing to install: your phone's camera, the PDF on this computer.

Point your camera at the document

No app to install. Nothing gets uploaded: the camera feed is analysed on this device.

A scanner that lives in the browser

Every scanner app asks the same two things: install me, and let me upload your documents. Neither is necessary. A phone browser already opens the camera, and everything after that is arithmetic. So that is what happens here. The live feed is analysed frame by frame on your device: the sheet is located, its four corners tracked, and a green outline shows exactly what will be cropped. Press capture and a projective transform straightens the page as if the camera had hung directly overhead. Then shadows come off and contrast comes up. Nothing is uploaded. Not the frames, not the pages, not the file.

How to scan a document with your phone

1

Open the camera

Your browser will ask permission once. Nothing is recorded and nothing is sent.

2

Frame the sheet

Three badges tell you what is missing: edges found, sharp, steady. Auto mode waits for all three.

3

Pick a mode

Document, receipt, invoice, card, ID, open book, whiteboard or photo. Each one sets its own threshold and contrast.

4

Order and export

Reorder, rotate, delete, reprocess a single page. Then one PDF at A4, Letter or fitted to the image.

What the arithmetic does

Finding the sheet starts with an adaptive threshold: each pixel is judged against the average of its neighbourhood rather than one global cutoff, which is the only way a photo lit from one side stays readable. The bright connected region that follows is the paper, its convex hull gives the outline, and four extreme points give the corners. Straightening is a homography. Eight unknowns, eight equations from four corner pairs, Gaussian elimination. Every output pixel is sampled back through that matrix, so the trapezoid your camera saw becomes a rectangle without stretching the middle. Output size comes from the side lengths, so a sheet shot at an angle keeps its real proportions. Shadow removal divides the image by its own estimated lighting, computed with a wide moving average. That one step is what separates a photo of a page from a scan of a page. Two checks decide when auto mode fires. Sharpness is the variance of the Laplacian: high on edges, near zero on a smeared frame. Steadiness is the mean absolute difference against the previous frame. Both must pass. A hand can hold a phone perfectly still and perfectly out of focus. Book mode hunts the darkest vertical column in the middle third. Find it, and the spread splits in two there.

Why this one

No install, no account, no upload. A browser tab is the whole app.

Auto capture waits for sharp and steady, not just steady.

Eight modes, and any page can be reprocessed without shooting again.

Questions about scanning to PDF

Short answers, limits included

Do I need to install anything?
No. It runs in the browser you already have. On a phone you can add the page to your home screen and it opens like an app, but that is a shortcut.
Do my scans get uploaded?
It depends on how you capture. With this device's camera, nothing is uploaded: the frames, the straightened pages and the finished PDF all stay here. If you pair your phone with the QR code, each page does travel through our relay: it is encrypted on the phone and decrypted only in this browser, so the relay only ever holds ciphertext, for fifteen minutes at most and up to forty pages. The question about pairing, further down, explains it in full.
Can I scan a book without cutting it?
Book mode hunts the fold and splits the spread in two. Curvature near the spine is reduced, not erased: a flatter page still scans better.
Will the text be searchable?
Not from this tool alone: what comes out is an image-only PDF. Send it through OCR PDF afterwards and the text becomes selectable, or continue in PDF ARENA where OCR sits one click away.
Why is my capture rejected as blurry?
Because the variance of the Laplacian fell below the threshold, which is the standard measure of focus. Back off slightly, tap to focus, add light. Auto mode fires on its own once it passes.
Can I use my phone camera and keep the PDF on my computer?
Yes, with nothing to install. The tool shows a QR code; your phone reads it and opens a capture screen. Each photo is encrypted on the phone with a key that travels inside the QR code itself, in the part of the link browsers never send, so the relay server stores ciphertext and holds nothing to open it with. Each page is deleted the moment your computer picks it up, and the session expires after fifteen minutes. Cropping, contrast and the PDF still happen in your browser.

Updated on

Do more with your PDFs

Discover all the professional tools we have prepared for you. All in one place.