Converting from CGM to Postscript
Published on 24th November 2009 Estimated Reading Time: 2 minutesOne thing that I recently had to investigate was the possibility of converting CGM vector graphics files into Postscript and from there into PDF. Having used ImageMagick for converting images before, that was an obvious option. However, that cannot process CGM files on its own and needs a delegate or helper application as well. This is the case with raw digital camera files too, with UFRaw being the program chosen. For CGM images, the more obscure RALCGM is what's needed, and tracking it down is a bit of an art. Though the history is that it was developed at the U.K.'s Rutherford Appleton Laboratory, it appears that it was left to go off into the wilderness rather than someone keeping an eye on things. With that in mind, here are the installation packages for Windows and Linux (RPM):
RALCGM is a handy command line tool that can covert from CGM to Postscript on its own without any need for ImageMagick at all. From what I have seen, fonts on graphical output may look greyer than black, but it otherwise does its job well. However, considering that it is a freely available tool, one cannot complain too much. There are other packages for doing vector to raster conversion and the ones that I have seen do have GUI's but the freedom to look at for cost software wasn't mine to have. The required command looks something like the following:
ralcgm -d PS -oL test.cgm test.ps
The switch -d PS uses the software's Postscript driver and -oL specifies landscape orientation. If you like to find out more, here's a PDF rendition of the help file that comes with the thing:
Thank you very much for maintaining this page. I have desperately sought a copy of RALCGM, but it appears the original maintainers have abandoned it. It was not so long ago this was considered worthy software, but things come and go quickly in the open-source software world. Thank you again.
Glad to have been of service but sorry to learn that this is the last outpost where this useful software is available. So long as I can, I'll keep this page on here for whoever needs it.