Scanning paper with your phone: how to get clean, readable PDFs

A scan has one job: someone else should be able to read it, print it and, ideally, search it. A wonky photo with a shadow across the middle fails all three. The good news is that almost every problem comes from four things you can fix in ten seconds.

1. Light from the side, never from behind you

If the light source is behind you, your own head and phone cast a shadow right onto the page. Stand so that the window or lamp is to your left or right. Daylight from a window is ideal; overhead office lighting is acceptable; the phone's flash is the worst option because it creates a bright hot spot in the middle of glossy paper.

2. Hold the phone flat, not at an angle

Photographing a page from an angle turns the rectangle into a trapezoid, and the text at the far edge comes out smaller and blurrier. Hold the phone parallel to the page, directly above it, and move closer until the page fills most of the screen. Tap on the text to focus before you shoot.

3. A dark, plain background

White paper on a white desk has no visible edge. Put the page on something dark and matte: a wooden table, a book cover, a dark t-shirt. It makes the page stand out and avoids reflections.

4. Flatten the paper

Folded letters and receipts curl. Put two coins on the corners, or press the page flat with a ruler just outside the frame. Curved lines of text are surprisingly tiring to read.

Turning the photos into a PDF

Open Scan to PDF on your phone and press Start camera. Take one photo per page with Take photo; the pages are added in order. For printed text, tick Make pages high-contrast black and white: the grey paper becomes white and the text becomes properly black, which reads better and prints better. Leave it off for photos, colour charts and anything with handwriting in pencil.

Choose A4 or US Letter as the page size if the PDF will be printed, so it fits a normal sheet. Then press Create PDF.

Already took the photos with your camera app? Use JPG to PDF instead, or HEIC to PDF if your iPhone saved them as HEIC.

After scanning

If you scanned a pile of single-sided sheets with a document feeder and ended up with blank backs, Remove blank pages will drop them in one go. And keep in mind that a scan is a picture of text: you can't select or search it until it has been through OCR. OCR PDF reads the pages on your device and adds an invisible text layer, so the scan becomes searchable without looking any different.