[NTG-context] invert colors in \externalfigure

Pablo Rodriguez oinos at gmx.es
Wed Jan 20 18:12:42 CET 2016

On 01/20/2016 02:09 PM, Marco Patzer wrote:
>> How can I invert the colors in the external figure without having
>> to edit the image file?
> Based on Peter Münster's grph-downsample.lua here some lines that
> should get you started. Note that you'll need graphicsmagick (or
> imagemagick for that matter. In the latter case change the call from
> `gm convert` to `convert`). This will do the conversion on the fly.

Many thanks for your reply, Marco.

I’m afraid it doesn’t work with PDF files. But it is fine for me, since
the solution provided by Wolfgang works fine.

Many thanks for your help,


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