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Convert a PDF to Black and White
Reduce a scan to pure black and white, for maximum contrast and minimum size.
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How it works
Every pixel is pushed to either black or white at a threshold you choose. On a faint or grey scan of printed text this can be transformative and produces very small files. It is also unforgiving: anything lighter than the threshold vanishes completely, so pencil notes, light stamps and photographs do not survive it.
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Questions
- What threshold should I use?
- Start at the default and raise it if text is disappearing, lower it if the page looks dirty.
- Will pencil notes survive?
- Often not. Check before relying on the result.
- Why is the file so much smaller?
- Two-tone images compress far better than greyscale or colour.