Scan to PDF
Photograph a document and get something that reads like a scan.
This tool runs entirely in your browser. Your file is never uploaded, and you can verify that in your browser's network tab. Verify it yourself: open your browser's network tab and watch. You will see one small request asking whether you have tasks left - a tool name and a hash, never the file.
What this does
Most people do not own a scanner and everybody owns a camera, but a photograph of a page is not a scan. This closes that gap in four steps: the page is found in the frame, the perspective is flattened, the text is straightened, and the image is thresholded so it reads as a document rather than as a picture of one. On a phone the camera panel captures directly; on a desktop it falls back to the file picker, because most people there are dropping photos they already took.
Use it when something has to be submitted as a scan and there is no scanner in the building: an identity document or a certificate for an application, a signed page going back to an office, a receipt for an expenses claim, or a handwritten note that has to be filed with everything else.
How it works
- Take the photo here, or drop photos you have already taken. Up to 100 at a time, each up to 100 MB, and every photo becomes one page in the order they are listed.
- Leave find the page and straighten on. A detection the tool is not confident about is discarded rather than guessed at, and the whole frame is used instead.
- Choose the mode. Black and white is the default and is what makes a photograph look like a scan; grayscale suits a page with photographs on it; colour keeps a stamp or a signature in its own ink.
- Pick the page size. A4 or Letter puts every photo on a standard sheet; Match makes each page the shape of its own photo.
- Turn on the searchable-text option if you will need to find or copy words later, and pick the language.
- Press Scan. The pages are assembled into a single PDF and the download starts.
The four steps run in that order because each depends on the one before. The document is a bright quadrilateral somewhere in a frame that also contains a desk, so its outline is detected first. A homography then maps that trapezoid back to a rectangle, which is what removes the leaning look of a photo taken at an angle. Only then is the residual rotation measured, and it is measured from the text lines rather than the page edges, because lines of text give away the true angle more reliably than a torn or shadowed edge does.
Thresholding is the step that decides whether the result is usable. A photograph has uneven lighting, so a single global threshold turns one half of the page black and blows the other half out. An adaptive threshold compares each pixel to its own neighbourhood instead, which is why a phone photo comes out looking like a scan rather than like a photocopy of a shadow. It is also why black and white is the default rather than an option for the brave.
The mode chooses the encoding as well as the look, and that is where the file size goes. A thresholded page is two colours and compresses to almost nothing as PNG, while JPEG would put ringing artefacts around every letter. A grayscale or colour page is photographic and is the other way round, so those are written as JPEG at quality 0.85. A black-and-white scan is routinely several times smaller than the same page in colour.
Resolution is set in dpi and defaults to 200, which is enough for ordinary printed text. Raise it to 300 for small print, faint carbon copies or anything the recognition is struggling with. 400 stores four times the pixels of 200 and rarely reveals something the threshold at 200 had not already found, so it is worth checking one page before committing a hundred. EXIF orientation is read and applied before any of the geometry, so a photo your phone tagged sideways is not straightened into the wrong rectangle.
Recognition, when you switch it on, runs on the processed pages rather than the originals - that is the whole point of doing the image work first, because a straightened, thresholded page recognises far better than a photograph of one. The words are placed as an invisible text layer over the image, so the page looks exactly as it did and the text can be selected, searched and copied. Words the recogniser scored below 40 per cent are left out rather than added wrong, since a wrong word in a searchable document is worse than a missing one.
What this tool cannot do
- Page detection can fail on a low-contrast background, a page that runs off the edge of the frame, or a heavily shadowed edge. It then falls back to the whole frame and says so rather than cropping to the wrong rectangle.
- Adaptive thresholding handles uneven light, not every kind of bad light. Hard glare, a strong reflection off glossy paper or a deep shadow across the text will still be visible in the result.
- Capturing directly needs a camera the browser can reach and your permission to use it. On a device without one, the tool falls back to the file picker and works on photos taken elsewhere.
Questions people ask
- Can I take the photo here, or do I need one already?
- Both work. On a phone or a tablet the camera panel opens in the page, shows the detected page outline live, and captures straight into the queue. On a desktop, or anywhere the browser cannot reach a camera, it falls back to the file picker so you can drop photos taken with something else. The processing afterwards is identical either way.
- How do I get a result that looks like a real scan?
- Lay the page flat, fill most of the frame with it, and keep all four corners inside the picture so the outline can be found. Even, indirect light beats a bright lamp, which throws a hard edge of shadow the threshold cannot remove. Avoid casting your own shadow across the page, and hold the camera roughly parallel to it - the perspective correction handles a tilt, but a smaller one leaves less to stretch.
- It cropped the wrong area, or did not crop at all. What now?
- A detection the tool is not confident about is thrown away deliberately, because a wrong auto-crop is worse than none: the whole frame is used instead and the result tells you how many pages were cropped. If a page was cropped wrongly, retake it against a background that contrasts with the paper. If you have already cropped your photos elsewhere, switch find the page off entirely.
- The PDF came out large. What should I change?
- Mode first: black and white is written as PNG of a two-colour image and is much smaller than the same page in colour or grayscale. Resolution second: 200 dpi is enough for ordinary text and 400 stores four times the pixels. If it is still too big after that, run the result through Compress PDF.
- Can I search the text afterwards?
- Yes, if you switch on recognition before converting. English, Indonesian and both together are available. The recognised words are written as an invisible layer over the page image, so the document looks unchanged but its text can be selected, searched and copied. Words scored below 40 per cent confidence are omitted rather than guessed at.
- Do my photos get uploaded, especially with recognition on?
- No, and recognition is the case where that would be easiest to get wrong. The image work runs in a Web Worker in your browser, and the recogniser's WebAssembly core and language data are served from this site's own origin rather than a public CDN - about 10.9 MB for English and 3.8 MB for Indonesian, cached after the first run. A photograph of your passport never leaves the device.