grayscale

Example

Take the colour out of a document that is going to a mono printer.

Given

• illustrated.pdf — a PDF with a photograph in it

From code

            import { loadDocument, runOperation } from '@pagecraft/core';

const illustrated = await loadDocument({ bytes, name: 'illustrated.pdf' });

const [output] = await runOperation('grayscale', [illustrated]);
          

From a shell

            pagecraft grayscale illustrated.pdf
          

What comes back

One PDF of 1 page.

This example is run by the test suite. If it stopped being true, the build would fail.

Options

This operation takes no options.

What it cannot do

• A photograph stored as a JPEG comes back a JPEG with every pixel neutral. It still carries three channels, because no browser codec writes a one-channel JPEG — storing it uncompressed instead would be several times the size.
• Named inks, patterns and shadings are left as they are. Guessing at the grey each was meant to be is how a print job comes back wrong, so the report says when one was met instead.
• An image written into the page itself, rather than stored beside it, is left in colour.
• Colours are converted with the standard luma weights and no colour management, which is what a viewer with no profile shows.