[magick-users] images in PDFs losing transparency in conversion

[duc.sequere.aut.de.via.decede at imagemagick.org]

> I am still have a problem going from RGB to CMYK.
> convert foo.jpg -colorspace CMYK bar.jpg
> ...still yields a file that my OS (Slackware Linux 12.2) 
> thinks is RGB. 

Perhaps there is a bug in your OS.  Let's see what ImageMagick says:

  identify -verbose bar.jpg

Does it report a CMYK JPEG image?