Convert a PDF to grayscale
Turn a colour PDF grey for printing without turning pages into pictures. Text stays selectable, and every page is checked for colour afterwards.
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Grayscale PDF in three steps
Printing in colour costs more, some print shops and exam portals ask for a grey file, and a document that has to survive a photocopier reads better when it was grey from the start. The usual online answer turns every page into a grey photograph. That prints fine and is no longer a document: the text cannot be selected, searched or read aloud, and a report that was 80 KB comes back at several megabytes.
Colours rewritten, not photographed
This changes the colours where the file writes them down. Every instruction that sets a colour for text, lines or fills is replaced with the grey of the same lightness. Pictures stored as samples are rewritten as grey pictures. Simple gradients get grey end colours. Forms, patterns and the appearance of comments and form fields are converted the same way. The page content is otherwise untouched, so the text is still text.
Checked, not assumed
A PDF can set colour in ways a rewrite cannot reach, such as a spot colour or a CMYK photo. So after converting, every page is rendered and looked at. If any colour is still visible, that page is either rasterised in grey at 150 dpi or left alone and named in the result. The choice is yours, and the result says which pages it affected, so nothing is quietly left in colour.
The file is converted by a worker in your browser and never uploaded.
- 1
Choose an unlocked PDF
- 2
Pick what happens to a page that still shows colour
- 3
Convert it and download the grey copy
Frequently asked questions
Does the text stay selectable?
Yes, on every page the conversion can rewrite. The colour settings in the file are changed to greys of the same lightness, so the words, fonts and vector drawings are the same objects as before. Only a page that still shows colour after the check is turned into a picture, and only if you leave that option on.
How are colours turned into greys?
By luminance, 0.299 red plus 0.587 green plus 0.114 blue, the Rec. 601 weighting most print drivers use. A dark blue heading becomes a dark grey rather than the same grey as a yellow highlight.
What happens to photos?
Pictures stored as raw samples become one-channel grey images, which are usually smaller. JPEG photos are decoded, made grey and saved again as JPEG at high quality, so they go through one more round of JPEG compression.
What can it not convert in place?
CMYK JPEGs, spot colours, mesh gradients and colour inline images. They are found by rendering every page after the conversion, and those pages are either rasterised in grey or listed in the result, whichever you chose.