Convert PDF to grayscale

Convert a PDF to greyscale

Print shops charge several times more per colour page, and a colour scan of a black-and-white document is pure waste. This re-renders every page in grey, usually shrinking the file substantially on the way.

Runs in your browserNothing is uploadedNo account, no watermark

Pages are re-rendered in grey, which means they become images and the text stops being selectable. A colour-heavy document usually halves in size; a text document will grow.

How to convert a pdf to greyscale

  1. 1

    Drop in the PDF

    Every page is rendered on your device — no upload, no queue.

  2. 2

    Pick a resolution

    150 DPI is right for screen reading and normal printing; 220 for anything going on good paper; 96 when the only goal is a small file.

  3. 3

    Convert

    Each page is rendered, converted to luminance grey and re-encoded as a JPEG.

  4. 4

    Download

    One PDF, greyscale throughout, ready for the cheap print queue.

Proper luminance, not an average

Each pixel is weighted 0.2126 red, 0.7152 green, 0.0722 blue — how the eye actually perceives brightness. Averaging the three channels instead turns yellow text nearly black and blue text nearly white, which is why naive greyscale conversions look wrong.

It converts to images

Greyscale is applied by rendering the page, so the output is a picture of each page. The text is no longer selectable or searchable. There is no way around this without rewriting every colour operator in the file.

Usually much smaller

Greyscale JPEGs carry one channel instead of three, so a colour-heavy document typically drops by half or more. A text document may grow, because a page of text is cheaper as text than as an image.

Questions

No. Pages are rendered to greyscale images, so the text layer is gone. If you need it, print to greyscale from your reader instead — most print dialogues have the option.

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