Created attachment 18166 [details]
/usr/share/cups/data/form_russian.pdf

The following command line converts a PDF input file into a CUPS Raster file with CMY color space (-dcupsColorSpace=4):

cat /usr/share/cups/data/form_russian.pdf | gs -dQUIET -dPARANOIDSAFER -dNOPAUSE -dBATCH -dNOINTERPOLATE -dNOMEDIAATTRS -dShowAcroForm -sstdout=%stderr -sOutputFile=%stdout -sDEVICE=cups -sMediaClass=PwgRaster -sOutputType=Automatic -r600x600 -dDEVICEWIDTHPOINTS=612 -dDEVICEHEIGHTPOINTS=792 -dcupsBitsPerColor=8 -dcupsColorOrder=0 -dcupsColorSpace=4 -dcupsBorderlessScalingFactor=0.0000 -dcupsInteger1=1 -dcupsInteger2=1 -scupsPageSizeName=na_letter_8.5x11in -I/usr/share/cups/fonts -c -f -_ > out.ras

If one displays the outcoming file with rasterview from

https://www.msweet.org/rasterview/

one gets messy output. Changing -dcupsColorSpace to any other color space (I tested Gray -> 0, RGB -> 1, CMYK -> 6, RGBW -> 17, SGray -> 18, SRGB -> 19, Adobe RGB -> 20) leads to correct output.

Using another input file (CityMap.pdf) one gets a correctly colored drawing of the map in CMY but the colors of the small photo on the page are wrong.