However, while postscipt generally works quite well as a printing mechanism, sometimes problems occur when using it as a distribution format. This document goes over some of those issues.
Several years ago, postscript standards weren't really well implemented, and there were lots of problems with transporting postscript from one plateform to another. Recently, things have improved substatially. The first thing to do is to make sure you are using the most recent version of your print drivers.
One of the biggest remaining problems has to do with page size. By default, most Americans will generate postscript formatted for 8.5 x 11 inch paper, while most Europeans will generate postscript formatted for A4 paper:
| Paper sizes | mm | inches | ||
|---|---|---|---|---|
| width | height | width | height | |
| A4 | 210 | 297 | 8.27 | 11.69 |
| Letter | 215.9 | 279.4 | 8.5 | 11 |
Sometimes, postscript will print even through it is formatted for a different size paper. For example when an A4 formatted document is printed on 8.5x11 paper, the printer will simply drop .7 inches of the document off the paper. However, whether this comes off the top or bottom of the page seems to be variable.
The best way to prevent problems is just to avoid making your margins too small. This is particularly important for people generating A4 postscript, since .7 inches of your document will be lost when printing on 8.5x11 inch paper.
dvips is a tool for converting dvi format files into postscript format files. Dvi files are normally generated by TeX and LaTeX. Dvips does a good job of producing transportable postscript (the most recent version is 5.66).
Since the fonts normally used by TeX and LaTeX aren't available in most laserprinters, the fonts must be embedded in the postscript. By default dvips generates bitmap versions of all fonts used in the document and embeds those in the postscript file. This has a number of problems. The font bitmaps generated are for a specific resolution, such as 300 dots/inch. If such a document is printed on a 600 dot/inch laserprinter, then your document won't look any better than that printed on a 300 dot/inch laserprinter. If the postscript contains 600 dot/inch bitmaps, it will be larger and may overwhelm older, 300 dot/inch laser printers. In addition, documents using bitmaps fonts won't look as good when previewed on screen using a tool such as ghostview.
The best solution would seem to be to have dvips embed actual postscript fonts in the document, rather than bitmaps. This is actually fairly easy to do. Somewhat surprisingly, the resulting postscripts files are much larger than ones that have embedded bitmap fonts (for most documents, the postscript fonts will add 300-600 Kbytes). However, if the resulting postscript file is run through Adobe's Distiller software to generate a PDF file, the resulting PDF file is as small or smaller than the PDF file resulting from a postscript file with embedded bitmap fonts. This PDF file can then be turned back into a small postscript file.
How does Distiller work such magic? Well, one of the tricks is that when a postscript file is turned into a pdf file, Distiller removes from any fonts characters that aren't actually used. This is also useful in that it means that distributing the document doesn't legally count as distributing a copy of the font, with all the copyright problems involved.