# duotone PDF files with lualatex

How to provide duotone PDF files for publishers who require it?

I have a document with images (graphicx \includegraphics), TikZ diagrams, compiled with lualatex.

So, if I understand it right, there are three things that have to be duotone colorspace:

• the general text in the document
• the images (have to be included as EPS? PDF?)
• (?) and the tikzpicture environment also need to use the right colorspace

The ConTeXt wiki gives clues about how to use duotone colors, but it would be great to stay with lualatex, and not re-do the whole document in ConTeXt.

Alternatively, it would be good enough to somehow hack a CMYK PDF file into duotone, if that is technically possible.

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If the publisher has requested duotones your best bet will be to produce or manipulate your images, using a program like Adobe's photoshop or just provide good resolutions of the original raw images to the publisher or color lab.

For scientific images you maybe able to produce the duotones using imageJ. Besides being open source is an excellent package and worth having it for other purposes also.

It is not possible with current PDF technology to automatically modify an included image and change it to a duotone, even with Acrobat Professional. You will need the full stack and knowledge of Adobe's workflow tools to do so. To see the difficulties try this minimal with an appropriate image, which converts an image to a two channel colour.

\documentclass[a4paper]{article}
\usepackage{graphicx}
\begin{document}
\includegraphics[width=5cm]{blue.jpg}% image with RGB colors
\includegraphics[decodearray=  0.5 1.0
0.0 0.0
0.0 0.0, width=5cm]{blue.jpg}%
\end{document}


This changes the color of the image (original at left) to an almost sepia color (image from wikipedia link above).

An additional consideration is that the final printed image, irrespective of the image format used, can very considerably from what your eye perceives on a screen. The sad truth is that no printing technology can reproduce the bright, saturated colors your monitor displays. Equally true that print can reproduce colors that a monitor cannot display, such as metallics and fluorescents and more importantly, dark saturated colors, particularly the yellows, oranges, greens and cyans.

Best advice I can offer is to suggest you talk to the publisher and get advice, as to what is the minimum that they would require and in what format. (normally they would require .tiff images).

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Very informative answer, thanks for elaborating on the issue. In the end I convinced them that CMYK will be good enough... :) –  Nyiti Mar 20 '12 at 8:25
@Nyiti Thanks! Glad you found it useful and CMYK is the way to go. –  Yiannis Lazarides Mar 20 '12 at 8:58