When to fix a scan
Feed a stack through an office machine and some sheets always go in crooked. Add the grey wash a scanner leaves and the result is awkward to read, worse to print, and larger than it has any need to be.
This measures how far each page is tilted, turns it straight, and cleans the paper white and the ink black. The file usually gets a lot smaller in the process.
How to use it
- 1Upload the scanned PDF.
- 2Choose black and white for text documents, or tidy greys where photos or a seal are mixed in.
- 3Leave straightening switched on.
- 4Clean up and download; the size before and after is shown.
Common questions
- How is the tilt found?
- Lines of text run horizontally, so on a straight page the dark pixels bunch onto the lines and thin out between them. The page is tried at a range of angles and the sharpest one wins.
- Won't black and white smear the text?
- The cutoff between paper and ink is worked out from this page's own brightness, so a dim photocopy and a bright scan don't share a threshold. The result is usually crisper than the original.
- Is the text still searchable afterwards?
- No. Pages are redrawn as pictures, so any text layer is lost. Run text recognition afterwards if you need to search it.