CHAPTER 2
46
Overview
support PDF directly). An application printing a PDF document to a PostScript
device must follow these steps:
1. Insert
procedure sets
containing PostScript procedure definitions to implement
the PDF operators.
2. Extract the content for each page. Each content stream is essentially the script
portion of a traditional PostScript program using very specific procedures,
such as
m
for
moveto
and
l
for
lineto
.
3. Decode compressed text, graphics, and image data as necessary. The compres-
sion filters used in PDF are compatible with those used in PostScript; they may
or may not be supported, depending on the LanguageLevel of the target output
device.
4. Insert any needed resources, such as fonts, into the PostScript file. These can
be either the original fonts or suitable substitute fonts based on the font met-
rics in the PDF file. Fonts may need to be converted to a format that the Post-
Script interpreter recognizes, such as Type 1 or Type 42.
5. Put the information in the correct order. The result is a traditional PostScript
program that fully represents the visual aspects of the document but no longer
contains PDF elements such as hypertext links, annotations, and bookmarks.
6. Transmit the PostScript program to the output device.