Scanning Documents with Your Phone: Resolution, Lighting and File Size

A phone can produce good document scans. A little care with light and settings keeps them readable and small.

Before you scan

1. Flatten the page. Smooth out folds and creases.
2. Use a plain, contrasting background, such as a dark table for white paper.
3. Use even light. Avoid shadows from your hand or phone.
4. Avoid glare on glossy paper. Tilt slightly or change the light.
5. Clean the camera lens.

Taking the picture

• Hold the phone parallel to the page, directly above it.
• Fill the frame with the document, leaving small margins.
• Keep the phone steady, or rest your elbows.
• Tap to focus on the text.
• Take a second shot if you're unsure.

Resolution

Use	Suggested resolution
Reading on screen	about 150 DPI
Archiving text documents	200 to 300 DPI
Small text, fine print	300 DPI

A page scanned at 300 DPI on A4 is around 2480 × 3508 pixels, which is plenty. Phone photos often exceed this, so you can resize.

Cropping and straightening

• Crop to the page edges.
• Straighten so lines of text are level.

Colour or black and white?

• Black and white for text documents produces small files, and text looks crisp.
• Greyscale suits pages with some shading.
• Colour for photos, stamps, coloured forms and anything where colour matters.

File size

A sharp, full-resolution colour scan can exceed several MB. To reduce: