3.4.1 Color hardcopy
When you produce a color picture (with plf or pli, for example) on your screen, you need to save not only the picture, but also the palette you used to draw that picture. Since the palette might change for each frame in a hardcopy file, the file must contain a complete palette as a sort of preamble to each frame. However, you usually want less expensive, higher quality black and white output, so the palette information is usually unnecessary. Yorick optionally converts colors to a standard gray scale before output to a hardcopy file, saving a little space in the output file.
If you are going to use a black and white printer, you can turn off palette dumping by means of the dump= keyword:
(you could also specify the name for the next hardcopy file). Unlike the name of the hardcopy file, the palette dumping flag persists across any number of hardcopy files. To turn on dumping again, you need to call hcp_file with dump=1.
All Yorick PostScript files will print on any PostScript printer, black and white or color. However, if you set dump=0, the palette was not dumped to the file, and it will print gray even on a color printer. If you print a dump=1 file on a black and white printer, the result will be very similar to dump=0; your colors will be translated to grays. You can put the call to hcp_file setting dump=0 in your `custom.i' file if you rarely want to dump the palette.