Convert a PDF to greyscale

by jenny on 12 January 2012 - 12:29pm in

gs -sOutputFile=grey.pdf -sDEVICE=pdfwrite \
  -sColorConversionStrategy=Gray -dProcessColorModel=/DeviceGray \
  -dCompatibilityLevel=1.4 color.pdf < /dev/null

Source: http://vince-debian.blogspot.com/2008/05/pdf-conversion-to-grayscale.html