Monthly Archives: July 2020

Convert PDF to grayscale using GhostScript

Published / by Kevin / Leave a Comment

[UPDATE] Huge caveat! While this is really meant to deal with RGB documents or objects, it does also convert CMYK and spot colors to grayscale. Unfortunately spot colors remain as separate plates that retain their name. This results in them being printed in color though on screen they appear gray. At least the colors (Pantone) and printer I tested on took spot channels and ripped them according to what they are named. If your printer does not have it’s own rendering library that matches your spot color names then I’m guessing they will print as grayscale.

It is possible to rasterize the art, which results in a pure grayscale, but you need such a high resolution even a simple business card with type and line art increases in size at least 30 times. I knew this was all too easy…

This script / app / droplet will convert a PDF or PostScript (.ps) document from whatever colorspace it lives in to grayscale. Has not been thoroughly tested. I mean, I ran it against a couple of files. One to work out the gs command, the other to test if it actually made a grayscale duplicate. That file was generated by MS Word so was of course RGB. The converted document was in fact true grayscale. I would say it converted to what you would get if you used a gray gamma 2.2 profile.
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