Convert PDF from sRGB color space to CMYK

colorspdfps

Does anyone know how I can convert a PDF (or EPS) file from sRGB color space to CMYK color space?

My workflow is currently the following:

Draw an image with Powerpoint
Print via postscript printer into a .prn postscript file
Execute a bash script that uses ps2eps, ps2pdf, and pdftk in order to generate a cropped PDF image

Unfortunately, this produces an sRGB PDF only. Instead, I need a CMYK PDF and I don't have an idea how I may get this.

Any help on this is highly appreciated.

Best Answer

You are already using Ghostscript in ps2pdf, so this answer would do it:

gswin32c.exe 
-o c:/path/to/output-cmyk.pdf 
-sDEVICE=pdfwrite 
-dUseCIEColor 
-sProcessColorModel=DeviceCMYK 
-sColorConversionStrategy=CMYK 
-sColorConversionStrategyForImages=CMYK 
 input-rgb.pdf

Related Solutions

Use convert to grab a specific page from a PDF file

ImageMagick is a tool for bitmap images, which most PDFs aren't. If you use it, it will rasterize the data, which is often not desirable.

Pdftk can extract one or more pages from a PDF file.

pdftk A=input.pdf cat A42 A43 output pages_42_43.pdf

If you have a LaTeX installation with PDFLaTeX, you can use pdfpages. There's a shell wrapper for pdfpages, pdfjam.

pdfjam -o pages_42_43.pdf input.pdf 42,43

Another possibility (overkill here, but useful for requirements more complex that one page) is Python with the PyPdf library.

#!/usr/bin/env python
import copy, sys
from pyPdf import PdfFileWriter, PdfFileReader
input = PdfFileReader(sys.stdin)
output = PdfFileWriter()
for i in [42, 43]:
    output.addPage(input.getPage(i))
output.write(sys.stdout)

Convert djvu to pdf

I tried printing the djvu file to PDF (using Evince, so it's probably a mix of djvulibre, gtk+ and cairo), but I got a way smaller result by converting the djvu pages to pdf using ImageMagick's convert.

For this, you need to

extract each page as a separate djvu document (I'm not sure if convert is able to deal multipage djvu and multipage pdf that easily), see djvmcvt -i (an "indirect" document is a document where each page is stored in a separate djvu file)
convert the page using convert — we're not losing anything here, remember that djvu is not vectorial, so even if you're generating an Adobe PDF, you're using it for a raster image
join the pages in a single PDF (you can just feed them to ghostscript -- for example, generating an A4 PDF named out.pdf with all pages from *.pdf in the current directory would be gs -q -sPAPERSIZE=a4 -dBATCH -dNOPAUSE -sDEVICE=pdfwrite -sOutputFile=out.pdf *.pdf)

This said, keep in mind that

This does just a straight conversion of a raster image — I guess the only thing you can tweak is the image quality, if it gets stored in the pdf using lossy compression (if convert is unable to do that, ghostscript has some options to tweak the output of pdfwrite, along the lines of -dPDFSETTINGS=, I'm not sure but these may include the possibility of enforcing lossy compression and defining the quality level)
This does not use djvu-specific knowledge, I guess the fact djvu encodes foreground and background separately can be used to generate the PDF in a clever way that somehow uses that to save some space
PDF is for vectorial stuff, djvu is way better suited for rasterized documents than PDF.

Best Answer

Related Solutions

Use convert to grab a specific page from a PDF file

Convert djvu to pdf

Related Question