Autofocus doesn't work with pages with little test

[elumbella]

I'm trying to scan a contract, where the last page contains basically only the signatures. When taking a photo, the app tries to autofocus, but fails, producing a blurred image in the first step and an almost white page after processing.

Steps to reproduce

Scan a page with little text on it

Expected behaviour

Camera should autofocus on the page and take a proper picture

Actual behaviour

Autofocus fails, producing only unusable results

Would you like to work on the issue?

I wouldn't even know where to start, but I could provide examples.