Convert CMYK PDFs to RGB with GhostScript
The following command will convert the PDF. Useful for cases when colors are wrong after the import by PDF Light Viewer plugin: gs -dSAFER -dBATCH -dNOPAUSE -dNOCACHE -sDEVICE=pdfwrite -sColorConversionStrategy=CMYK -dProcessColorModel=/DeviceCMYK -sOutputFile=some.rgb.pdf some.pdf
GhostScript Installation
GhostScript is a server software. It’s a library to work with PDF files. Usually you want to install it on the server where you host your WordPress.