Turn PDF into grayscale

[Sundar Nagarajan]

Pupeno wrote:
> Hello,
> I have some color PDFs I'd like to turn into grayscale, any ideas how ?
> I have tried printing to PDF (the pdf itself) and setting it to grayscale, but 
> the PDF ends up in color anyway.
> Thank you.
> 

You can do this quite simply at the command line using the Imagemagick 
tools. Install imagemagick ('apt-get install imagemagick' should do the 
trick).

to convert a file named color.pdf to grayscale and store the output in a 
file named gray.pdf:

convert -colorspace GRAY color.pdf gray.pdf

The only drawback I see is that this always seems to choose a gray 
colorspace with 256 colors (while the original colorspace may have 
(e.g.) 64K colors. Maybe someone else can comment whether the GRAY 
colorspace is always 8-bit.