Print-ready PDF

glu writes files that a print shop can take as they are. Everything that matters for print is CSS, so a document needs no Lua and no second tool between the layout and the press. A small flyer has all of it in a few lines:

<head>
  <meta name="pdf-format" content="PDF/X-4">
  <title>Open day at the press</title>
  <style>
    @-bag-color blue { model: spotcolor; colorname: "PANTONE 300 C"; c: 100; m: 44; y: 0; k: 0; }
    @-bag-color ink  { model: cmyk; c: 0; m: 0; y: 0; k: 100; overprint: yes; }

    @page { size: a6; margin: 12mm; bleed: 3mm; marks: crop; }
    body  { color: ink; }
  </style>
</head>

The how-to Prepare a PDF for the print shop walks through a complete file. The pages of this chapter explain each part:

  • PDF/X covers the two conformance levels, the output intent and how to check the result.
  • Color covers CMYK and spot colors, overprint and how to look at the plates.
  • Bleed and crop marks covers the trimmed page, the bleed and what runs into it.
  • Register covers lines that stand level across columns and on both sides of a leaf.

Handover checklist

Ask the print shop first: which PDF standard, which output condition, how much bleed, and whether they want crop marks. Then go through the file:

Check How
The conformance level is what the shop asked for <meta name="pdf-format"> or format:, see PDF/X
The document has a title <title> or title:, otherwise the title is a placeholder
The output intent matches the printing condition FOGRA39 by default
The page size is the trimmed size size in @page, see Bleed and crop marks
Backgrounds and pictures at the edge reach into the bleed pdfinfo -box, and a look at the pages
Colors are CMYK or spot colors where the exact color matters Color
The name of each spot color is the one the shop uses colorname in @-bag-color
Small black text overprints Overprint
Pictures have enough resolution at their final size, usually 300 dpi Your image editor; glu places what it gets
The plates look as expected Look at the plates
The file passes the preflight of the shop’s profile Check the file

Fonts need no check: glu embeds them, as a subset, in every PDF.

What glu leaves to the print shop

glu does not trap colors, does not impose pages on a sheet and does not convert RGB pictures to CMYK. Those steps belong to the print shop or to your own prepress tools, and PDF/X is the format that hands the file over for them.

DebuggingPDF/X