pstotext.hlp

GSview 4.6 PostScript previewer。Ghostscript在MS-Windows, OS/2 and Unix下的图形化接口

1 PSTOTEXT

  PSTOTEXT - extract ASCII text from a PostScript or PDF file

  Syntax:
 
   pstotext [option|pathname]...

   where option includes:
        -cork
        -landscape
        -landscapeother
        -portrait
        -
        -gs command
        -debug
        -bboxes
        -output file

2 Description

PSTOTEXT reads one or more PostScript or PDF files, and writes to
standard output a representation of the plain text that would be
displayed if the PostScript file were printed.  As is described
in the DETAILS section, this representation is only an
approximation. Nevertheless, it is often useful for information
retrieval (e.g., running grep(1) or building a full-text index)
or to recover the text from a PostScript file whose source you
have lost.

PSTOTEXT calls Ghostscript, and requires Aladdin Ghostscript
version 3.51 or newer.  Ghostscript must be invokable on the
current search path as gs.  Alternatively, you can use the "-gs"
option to specify the command (pathname and options) to run
Ghostscript.

PSTOTEXT reads and processes its command line from left to right,
ignoring the case of options.  When it encounters a pathname, it
opens the file and expects to find a PostScript job or PDF
document to process.  The option "-" means to read and process a
PostScript job from standard input.  If no - or pathname
arguments are encountered, PSTOTEXT reads a PostScript job from
standard input. (PDF documents require random access, hence
cannot be read from standard input.)

The option -cork is only relevant for PostScript files produced
by dvips from TeX or LaTeX documents; it tells PSTOTEXT to use
the Cork encoding (known as T1 in LaTeX) rather than the old TeX
text encoding (known as OT1 in LaTeX). Unfortunately files
produced by dvips don't distinguish which font encodings were
used.

The options -landscape and -landscapeother should be used for
documents that must be rotated 90 degrees clockwise or
counterclockwise, respectively, in order to be readable.

The options -debug and -bboxes are mostly of use for the
maintainers of PSTOTEXT.  -debug shows Ghostscript output and
error messages. -bboxes outputs one word per line with bounding
box information.

2 Details
PSTOTEXT does its work by telling Ghostscript to load a
PostScript library that causes it to write to its standard output
information about each string rendered by a PostScript job or PDF
document.  This information includes the characters of the
string, and enough additional information to approximate the
string's bounding rectangle.  PSTOTEXT post-processes this
information and outputs a sequence of words delimited by space,
newline, and formfeed.

PSTOTEXT outputs words in the same sequence as they are rendered
by the document.  This usually, but not always, follows the order
that a human would read the words on a page.  Within this
sequence, words are separated by either space or newline
depending on whether or not they fall on the same line.  Each
page is terminated with a formfeed. If you use the incorrect
option from the set {-portrait, -landscape, -landscapeother},
PSTOTEXT is likely to substitute newline for space.

A PostScript job or PDF document often renders one word as
several strings in order to get correct spacing between
particular pairs of characters.  PSTOTEXT does its best to
assemble these strings back into words, using a simple heuristic:
strings separated by a distance of less than 0.3 times the
minimum of the average character widths in the two strings are
considered to be part of the same word. Note that this typically
causes leading and trailing punctuation characters to be included
with a word.

The PostScript language provides a flexible encoding scheme by
which character codes in strings select specific characters
(symbols), so a PostScript job is free to use any character code. 
On the other hand, PSTOTEXT always translates to the ISO 8859-1
(Latin-1) character code, which is an extension to ASCII covering
most of the Western European languages.  When a character isn't
present in ISO 8859-1, PSTOTEXT uses a sequence of characters,
e.g., "---" for em dash or "A\\226" for Abreve.  PSTOTEXT can be
fooled by a font whose Encoding vector doesn't follow Adobe's
conventions, but it contains heuristics allowing it to handle a
wide variety of misbehaving fonts.

(PSTOTEXT no longer translates hyphen (\\255) to minus (\\055).)

2 Options

    -cork            assume Cork encoding for dvips output
    -landscape       rotate 270 degrees
    -landscapeother  rotate 90 degrees
    -portrait        don't rotate (default)
    -bboxes          output one word per line with bounding box
    -debug           show Ghostscript output and error messages
    -gs "command"    Ghostscript command
    -output file     output results to "file" (default is stdout)
    -                read from stdin (default if no files specified)

2 Authors

Andrew Birrell (PostScript libraries), Paul McJones (application),
and Russell Lang (Windows and OS/2 adaptation).

VMS port by Hunter Goatley.

2 See_Also
PSTOTEXT incorporates technology originally developed for the
Virtual Paper project at SRC; see

http://www.research.digital.com/SRC/virtualpaper/

As mentioned above, PSTOTEXT invokes Ghostscript.  See gs(1) or
http://www.cs.wisc.edu/~ghost/.

2 Copyright

Copyright 1995 Digital Equipment Corporation.

Distributed only by permission.

See file pstotext.txt for details.