Plain black text is encoded as RGB instead of Gray and so printing with full-color in paged.js

[geealbers]

Before proceeding, check to make sure there isn’t an existing issue for this bug.

• I have searched the existing issues and determined this is a new bug.

Steps to reproduce

1. Start a new project
2. Run quire build and quire pdf to generate a PDF
3. Open the PDF in Acrobat and use the Print Production > Output Preview tool to hide the Black (K) separation

Actual behavior

The main body text of the PDF (though set as #000 is revealed to be made up of a full-color build of CMYK. Meaning it has a little of each color in it.

It appears that in Paged.js/Chrome the blacks are being encoded as RGB colors and being interpreted as full CMYK builds and so using 4-color inks when it should not. For the PrinceXML handling of this, see https://www.princexml.com/doc/graphics/#rich-black-and-true-black, where they talk of the RGB color being "encoded in the DeviceGray color space"

When the value use-true-black is used, such an RGB value will be encoded in the DeviceGray color space in the PDF. A CMYK printer should print the gray level using only the black ink. This is the default setting of Prince.

Expected behavior

Removing the Black (K) separation with the Print Production > Output Preview tool should make the text dissappear entirely, thus confirming it is only printing with Black ink, and not any of the other colors

Version numbers

Quire CLI 1.0.0-rc.7
Quire 11ty 1.0.0-rc.9
Node 18.16.0

What browsers are you seeing the problem on?

No response

Relevant Terminal/Shell output

No response

Supporting Information

Paged.js without Black ink:

PrinceXML without Black ink:

[fchasen]

A few option for handling this at the moment:

• OSP PDFUtils is an open source tool using Ghostscript to do PDF post-processing.
• Adobe Acrobat: In Preflight Fixup -> Custom Fixups allows creating a color map tol to replace the blacks
• Pitstop Pro has a more automated conversion

Ideally we'd use Ghostscript.js npm library to include the Ghostscript commands for color processing directly in the Paged.js CLI but I don't think the Ghostscript dual licensing will allow for that, so either we can make it a separate optional plugin or eventually use PDF-lib to parse, converting and replace colors.

[geealbers]

Thanks @fchasen. I'm going to take you off the issue but am reopening it until we can figure out and document a reasonable process for Quire users to convert rick-black to black-only text in their PDFs. My own first attempts through Acrobat were woefully unsuccessful. I'm wondering though if our production department might be able to advise so I will follow up with them as a next step.

[Erin-Cecele]

We are currently working on a fix for your bug! Stay tuned for updates and thank you for your important contribution.