Occasionally asked questions about PostScript images and PostScript files

Dan Ellis <dpwe@icsi.berkeley.edu> 1997nov21

I spend a lot of time trying to fix PS files for various documents (my own and for other projects that I'm involved in). To my horror I realized I was re-solving problems that I had worked through previously but forgotten. Time for technological memory aids! These questions are perhaps not the first ones you'd ask, but they do come up and might not be well covered in other references.

You'll notice that I haven't actually written the answers yet. I've made notes on what I intend to say. Maybe even just knowing that there's something to be said can be helpful ...

1. What do I need to know about postscript?
   • set of commands
   • rich language -> arbitrary complexity
   • typically, define a set of operators & use
   • DSC
   • (pdf)
2. I have this postscript file but it doesn't come out correctly on my printer. What's the problem? How can I diagnose it?
   Possible problems:
   • The file is getting messed up in transit e.g. a binary-encoded postscript file going over some translating network link.
   • Memory overflow in printer, esp for complex grayscale plots.
   • Inappropriate DSC comments (HPLJIVP %%EOF)
   • Erroneous postscript
3. I have a postscript image that prints/previews fine on its own, but fails when I include it in a file. Why?
   • conflicts between dictionary definitions (e.g. Frame 3.0)
   • not EPSF - clears screen - specifies paper
   • illegal/protected commands
4. My file does one thing under Ghostscript, but another (or nothing) under Ghostview. What's up?
   • erroneous DSC comments
5. This file was generated by Frame 3 on a NeXT.
   • problem with redefinition of CS.
6. This file was generated by Matlab 4.
   • need to strip DSC comments
7. This file was generated from a Tk4.2 canvas.
   • fails to include header
8. This postscript version of a scanned image or screenshot is outrageously large.
   • RGB (24 bit) encoding. Use photoshop to convert to the 300 dpi bitmap; use pbmplus to convert to rle postscript, or use distiller to jpeg compress.