eurion.sty

A LaTeX package that overlays the EURion constellation — the five-circle anti-photocopy pattern from banknotes — onto your document pages. Visual reproduction only; this is a stylistic gag, not real anti-counterfeiting protection.

Install

Drop eurion.sty next to your .tex file, or into your local texmf tree (~/texmf/tex/latex/eurion/eurion.sty).

Requires: tikz, eso-pic, xkeyval, xcolor (the last is pulled in by tikz already).

Quick start

\documentclass{article}
\usepackage{eurion}                 % scatter mode, gist-yellow, default density
\begin{document}
... your document ...
\end{document}

Three layout modes:

\usepackage[scatter, color=yellow, density=25, seed=42]{eurion}
\usepackage[corner=top-right, color=green]{eurion}
\usepackage[manual]{eurion}

In any mode you can also drop an extra constellation by hand:

\eurion[color=orange, size=2, rotate=15]{current page.center}
\eurion[color=green]{[shift={(3cm,-3cm)}]current page.north west}

The second argument is any TikZ coordinate; the macro draws inside its own remember picture, overlay tikzpicture.

Options

The flags [scatter], [corner], and [manual] are accepted as shortcuts for mode=. Writing [corner] alone selects corner mode at the default top-right; writing [corner=top-left] selects the mode and sets the corner.

Caveats

• Color channel only. Real banknote detectors look for the rings in a color channel, not in greyscale. A B&W print or grayscale export of your PDF will hide the pattern.
• Not real anti-copy. Modern image-editor blocks (Photoshop, Paint Shop Pro) actually rely on Digimarc digital watermarks (CBCDG), not on the EURion constellation alone. This package is decorative.
• The exact spec is secret. Three publicly available reproductions disagree on exact coordinates; this package uses the geometry from Petr Kutalek's PostScript gist.

Examples

Build any of them with pdflatex example.tex (or lualatex / xelatex).

License

WTFPL — see LICENSE. The author does not endorse this license; it was picked because CTAN distribution requires some license to be selected, and the WTFPL is the lowest-friction option that satisfies that requirement. (CTAN's metadata vocabulary doesn't carry a wtfpl key, so the catalogue lists it under other-free.)

References

• https://en.wikipedia.org/wiki/EURionconstellation
• Markus Kuhn's original write-up: https://www.cl.cam.ac.uk/~mgk25/eurion.pdf
• Petr Kutalek's eurionize shell+PostScript gist (geometry source): https://gist.github.com/petrkutalek/93b7eebf22f4dbcfab8cd80a91fd27a8
• Conor Armstrong's Python eurion (option-surface inspiration): https://github.com/conorarmstrong/eurion
• Steven Murdoch on what actually triggers detection: https://murdoch.is/projects/currency/