Convert a PDF to grayscale

How to convert a PDF to grayscale

1. Pick a version above. Colour only is selected to begin with, because it changes nothing but colour.
2. Choose your PDF, or drop it on the page. It is processed in your browser and never uploaded.
3. Drag the slider to compare the original with the grey version. Look at anything that relied on colour.
4. If the grey is too light for printing, choose Balanced or Crisp print, then press Apply new settings.
5. Download the new PDF. The original is left untouched, and it keeps the colour.

Grayscale or black and white?

They are often confused, and they behave very differently.

• Grayscale keeps every shade of grey between black and white. Photographs, shading, signatures and stamps survive as tones.
• **Black & white** is a threshold: every pixel is forced to pure black or pure white, with no grey at all. It gives crisp text and a clean page, and it destroys shading and photographs.
• If you are not sure, start with grayscale. It is the safer of the two.

The three versions

• Colour only — each pixel becomes its own luminance. Nothing else changes: not the paper, not the ink, not the contrast.
• Balanced — grey with moderate darkening and a cleaner background. A good choice for printing.
• Crisp print — grey with darker text, whiter paper and a little sharpening, tuned for a mono printer.
• Move a slider and the version shows as Custom. Your numbers are used exactly as set.

Check colours that carry meaning

A mono printer converts colour to grey by luminance, and very different colours can land on almost the same grey. Mid-blue and mid-red are the classic pair. If a legend, a highlighted row or a status column relies on colour, look at the grey preview before printing many copies.

Digital pages and scanned pages

• Pages made of text and vector graphics have their colour instructions converted, so the text stays real, selectable text and stays sharp at any zoom. Colour that is applied in unusual ways, such as some gradients, patterns and special colour spaces, may keep its colour; check the preview.
• Pages that contain images, including every scan, are rendered at 200 DPI and written back as grey images. Their text becomes part of the image.
• If a page has no colour, it is left untouched, and the result panel says so.

What it does not do

• It cannot bring the colour back. Keep the original, which is never modified.
• It does not make files smaller, and can make them larger. Pages that contain images are re-rendered at 200 DPI, so a scan can come out bigger than the original: the demo sample went from 86 KB to 339 KB. If size matters, black & white is far smaller for plain text pages.
• It is not a replacement for professional colour separation. For press work, talk to the printer.