Info: Scribus is now used for CMYK export. To my knowledge, this third-party extension is no longer maintained.
Extension "Export to PDF in CMYK"
The Extension "Export to PDF in CMYK" generates a vectorial file in PDF format using the CMYK color system. The resulting elements of the PDF file maintain the exact values applied in the art on Inkscape, different of the default export made by Inkscape that uses Cairo and applyes just RGB values to the elements. The extension uses the software UniConvertor to generate the PDF file. The extension can be inproved, but it already gives acceptable results.
Before you install the extension, install the last version of Uniconvertor software and ImageMagick on your system.
- If you use Windows, wait some time. This extension doesn't yet run on Windows.
- If you use Linux:
Copy the two files to the folder
Before generates PDF files, you need to convert every element on path (or curve). A shortkey to it is Ctrl+A and Ctrl+Shift+C.
Click "File" - "Save as..." and choice the kind of file "PDF CMYK (*.pdf)". The following window will appear:
Look the details of the options:
Rasterize filter effects
Define if you want to convert the marked objects into bitmap.
Export just selected
This option make the extension generate a bitmap of just "background" layer. If this option is not marked, the PDF will have every appearing elements shown on the bitmap.
Resolution for rasterization (dpi)
This is the DPI value that you want on bitmaps of the final PDF file. As much DPIs much more quality amd major size of file. To graphic printing, 300 DPIs is enough.
If this option is enabled, the CMYK colors on bitmaps will disrespect the existence of pure black (100%K). This way, the result will be the CMYK colors without the black "leaked". Very useful option to graphic printing.
Applyes the selected profile in Color Management of Inkscape in the image.
What profile does this extension uses?
The defined profile on "Color Management", at the settings window of Inkscape.
Why does the extension take so many time to generate the image?
It uses external process to generate the files. Speaking in a simple way, it opens another Inkscape, export images in PNG format, uses another software, ImageMagick to convert the images from PNG to JPEG and the UniConvertor to generate the PDF.
Alternative way to create a CMYK-PDF
In case the extension doesn't work, there are still ways to obtain a CMYK-PDF out of Inkscape.
Conversion via Ghostscript
Ghostscript can convert any PDF from RGB to CMYK. We can use this the follwing way:
Step 1: Export PDF out of Inkscape.
Step 2: Transform it into CMYK via command-line.
For instructions, visit:
This does also work on Windows.