Scan ClanHow to remove glare and shadows from a scanned page
Two things ruin a phone scan: the shadow you cast over the page, and the bright patch a lamp leaves on glossy paper. Scan Clan has a filter for each — No Shadow and Glare Removal — and a few centimetres of movement prevents both.
Fixing a scan you already took
Open the page in the editor
Filters can be changed at any time, on any page, and any page can be reverted to the original photo.
Try No Shadow
This is the one for an uneven wash of grey across part of the page — usually your own hand or head between the light and the paper.
Try Glare Removal
This is the one for a bright blown-out patch on glossy or laminated paper.
Or Magic White for a mild case
If the page is just a bit grey overall rather than patchy, Magic White whitens the paper and keeps the ink dark.
Preventing it instead
Light the page from the side, not from directly above. Overhead light on glossy paper reflects straight back into the lens, and a blown-out white patch has no detail left in it to recover — no filter can reconstruct what the sensor never recorded.
Stand so your own shadow falls away from the page. Most shadows in phone scans are cast by the person holding the phone.
For laminated cards and glossy photographs, tilt the page slightly rather than shooting it flat on. Edge detection straightens the perspective afterwards, so an angled shot costs you nothing and moves the reflection out of frame.
Diffuse light beats bright light. An overcast window is better than a bare bulb.
What each filter is for
There are twelve: Original, Magic Color, Magic White, Black and White, Greyscale, Whiteboard, Blackboard, Lighten Text, No Shadow, Screen, Vivid and Glare Removal. Lighten Text helps a faded receipt or a worn carbon copy. Whiteboard and Blackboard are for photographing a board rather than paper. Screen is for a photo of a monitor.
See also: how to scan a document to PDF on Android.