[Tex/LaTex] How to make sure images are CMYK

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I am submitting a paper to a conference in a few days and just noticed they require all images to be in CMYK color space. Is there a quick easy way to check if they are?

And if they are not, is there a quick easy way to convert them to CMYK, preferably via PDFlatex or another Latex component (best) or via a batch utility (good) or something so I don't have to do it manually (bad). If a batch is the solution, I'd like to be able to take a copy of my working folder tree, point a batch utility at it, and have it convert everything therein to CMYK if it's not already.

My images are mostly jpeg, but I think I might have some PNGs as well.

Best Answer

PNG's cannot be in the CMYK colorspace, so if you have some you will need to convert them to JPGs.

I only use linux so my solution may not be relevant but imagemagick is a good commandline tool to batch convert images.

if you use colour within your document you will need to load the xcolor package with the cmyk option to make sure that all colour definitions are translated to the CMYK colorspace (although it will not convert included images, only colours of used directly in the latex document.

One other note if you use fontspec, for font definitions, using the [Color=...] options as fontspec doesn't support CMYK colours. instead you will need to use the \color{} command from xcolor instead.

An example of imagemagick commandline conversion would be:

convert image-rgb.jpg -colorspace CMYK image-cmyk.jpg

You have to be aware that that the converted image will look different to the original one.

You can check what colorspace the image is encoded in by using the identify command:

identify -verbose image.jpg

and look for the Colorspace: field. In a POSIX environment with grep available simply doing

identify -verbose image.jpg | grep "Colorspace:"

should give you the answer.

Edit: As noticed, the default conversion done by IM via the -colorspace option is not very good. The IM manual advise to use the -profile <filename>.icc option instead to get better results. This requires having the appropriate icc profile file available.

On a linux distribution with ghostscript installed, there is a default_cmyk.icc file which gives already a much better result than the one obtained using the -colorspace CMYK option. However, Adobe make their ICC profiles availble for free, and these can be used by IM to produce even better results. The Adobe ICC profiles are available from the Adobe website. The package comes with 8 RGB profiles and 14 CMYK ones so plenty to choose from. I am tried both the WebCoatedSWOP2006Grade5.icc and the USWebCoatedSWOP.icc, and both give very good results with slight difference between them. However, if the conference insist on CMYK colorspace, it might be worth asking them if they can provide you with their ICC profile, you will therefore make sure that all the colours in your images will print properly.

Once you have the ICC file available, you can then use them with imagemagick like this:

convert image-rgb.jpg -profile "\path\to\cmyk_profile.icc" image-cmyk.jpg

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[Tex/LaTex] Can pdflatex (or any tex package) automatically rescale included images which have been reduced in size

I've tried a little black magic with LaTeX, and found out how to do it without external scripts ─ though it still is somewhat dirty and not that easy to use. Basically, you would need to call ImageMagick from inside LaTeX.

To do this, you need to call it with --shell-escape parameter. This allows for using a command named \write18, that executes a parameter passed to it. Then you could add the following code to the preamble:

\newcommand{\doConvert}[2]{\immediate\write18{convert #1 -resample %
  300x300 -resize #2 #1.rs}}
\newcommand{\imgRs}[4]{\doConvert{#1.#2}{#3x#4}%
  \includegraphics[width=#3, height=#4, type=#2, ext=.#2.rs, read=.#2.rs]{#1}%
}

This enables you to call \imgRs{file}{extension}{width_in_pts}{height_in_pts} in order to convert the image to 300 dpi and include it in the document.

Of course you could always specify the dimensions in inches or any other units: you would just have to change the call to \doConvert in imgRs to account for scaling from unit used to points -- and you would have to use the dimensions consistently. It could be possible to actually find out what were the units used, or make some parameters optional, but it's independent of this solution.

[Tex/LaTex] Is it possible to have pictures in .pdf and .eps in LaTeX

The image types you can include depend on whether you use latex or pslatex, and if you use latex they depend on the dvi driver (usually dvips) that you use. So it is better to omit the extension

\includegraphics[scale=1.8]{figura/pantalla1}

Rather than

\includegraphics[scale=1.8]{figura/pantalla1.eps}

then if you use pdflatex it will find a pdf (or png) version and if you use latex it will find a eps (or png).

Of course for bitmaps it may be best if possible to generate them at the correct size rather than scale them on inclusion as they do not necessarily scale so well.

Do not use [H] on figures unless you are absolutely sure you want that, and if you are sure you want that, try to persuade yourself otherwise:-)

Best Answer

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