I have been trying to convert a color pdf to a grayscale pdf prior to printing to avoid the color printing costs. I am using Debian and ImageMagick commands:
convert -monochrome swp574.pdf output2.pdf
convert -colorspace GRAY swp574.pdf swp574GRAY.pdf
pdf2ps swp574.pdf output2.pdf
and I get this response on the terminal each time.
File has circular references in resource dictionaries. **** File has circular references in resource dictionaries. **** This file had errors that were repaired or ignored. **** Please notify the author of the software that produced this **** file that it does not conform to Adobe's published PDF **** specification.
How can I get over this problem?