pkfix-helper

PKFIX-HELPER(1) PKFIX-HELPER(1)

NAME
pkfix-helper - preprocess dvips-produced PostScript documents before
passing them to pkfix

SYNOPSIS
pkfix-helper [--help] [--verbose] [--force=name=fontspec]
[--ps=filename.ps] [--tex=filename.tex] [--cache=filename]
[--include=fontspec] [--exclude=regexp] [--keep=fontspec] [--quiet]
[--no-repeats] [--spp=number] [input.ps [output.ps]]

DESCRIPTION
Motivation
PostScript documents created with old versions of dvips almost
invariably utilize bitmapped (PostScript Type 3) fonts. The problem
with bitmapped fonts is that they target a specific device resolution;
a PostScript file produced using 300 DPI fonts will look grainy on a
600 DPI printer. Even worse, all bitmapped fonts look grainy when
zoomed in on screen. The solution is to use vector (PostScript Type 1)
fonts, which are resolution-independent and appear crisp at any size or
scale.

While it is no longer difficult to configure dvips to use vector fonts,
it is not always possible to rerun dvips on an old .dvi file. The .dvi
file and document source may have been lost; or, the source may no
longer compile because packages it depends upon may no longer be
available.

Heiko Oberdiek's pkfix script replaces bitmapped fonts in
dvips-produced PostScript files with the corresponding vector fonts.
It works by parsing the PostScript comments with which dvips surrounds
bitmapped-font definitions. For example, a font definition beginning
with the comment "%DVIPSBitmapFont: Fi cmss10 11 28" and ending with a
matching %EndDVIPSBitmapFont is known to define font "Fi" as "cmss10"
(Computer Modern Sans Serif at a design size of 10 points) scaled to
11 points. Only the 28 characters actually used by the document are
defined. pkfix then replaces the font definition with one that defines
"Fi" using the same set of characters but taken from the cmss10.pfb
vector font file.

Unfortunately, pkfix works only with versions of dvips newer than v5.58
(ca. 1996). Naturally, the older a PostScript document, the less
likely its sources still exist and can still be recompiled. Older
versions of dvips lack %DVIPSBitmapFont comments and various other
PostScript comments on which pkfix relies. Without PostScript comments
to guide it, pkfix is unable to determine which vector fonts correspond
with which bitmapped fonts.

Overview
The pkfix-helper script is a preprocessor for pkfix that attempts to
determine the association between each document-font name (e.g., "Fi")
in a PostScript file and the original font (e.g., "cmss10") and fonts
size (e.g., 11 points). It then fabricates the PostScript comments
that pkfix expects to see so that pkfix can do its job.

pkfix-helper works by comparing every document font against every .tfm
font file it knows about (assuming that each such font has a
corresponding .pfb vector version) and selecting the best matching .tfm
file for every document font. pkfix-helper has access only to the
widths of characters and only to those characters actually used in the
document. Also, the program recognizes only a limited set of the most
popular .tfm files and scaling factors. Consequently, the comparison
is imperfect and pkfix-helper may attribute an incorrect font to a
given name. Fonts comprising only one or two characters actually used
in a document are particularly problematic for pkfix-helper because
many fonts may be near-enough matches to fool the problem.

pkfix-helper is designed so that a user can guide the font-selection
process by manually designating matching fonts. With a modicum of
diligence and patience a user can correct any mismatched fonts and help
the program provide proper input to pkfix.

OPTIONS
pkfix-helper accepts on the command line the filename of a PostScript
document to process (with the default being the standard input device)
and the filename of a modified PostScript document to create (with the
default being the standard output device). The program also accepts
the following command-line options:

Frequently Used Options
-h, --help
Display usage information and exit. The --verbose and --quiet
options can be used to increase and decrease the amount of
information presented.

-v, --verbose
Increase the amount of status information that pkfix-helper
displays as it runs. Additional instances of --verbose on the
command line further increase the program's verbosity. By default,
only major operations are displayed. A single --verbose
additionally displays information about individual font
comparisons. A second --verbose additionally displays details
about some of the program's internal operations.

-f name=fontspec, --force=name=fontspec
Force pkfix-helper to associate a specific font with a given font
name appearing the document. name is a two-character dvips font
name such as "Fa". fontspec is a font specification such as
"cmmi8" or "cmsy10 @ 1.1X". An asterisk used in the name of the
base font (e.g., "cmti*") will automatically try all integral test
font sizes from 5 to 17 points ("cmti5", "cmti6", ..., "cmti17").
An asterisk used as a scale value (e.g., "cmsy10 @ *") will be
replaced by the scale value that gives the best match to the
original font's metrics. The --force option can be specified
repeatedly on the command line.

-p filename.ps, --ps=filename.ps
Create a PostScript file called filename.ps that shows the dvips
name and a font sample of every font used by the input document.

-t filename.tex, --tex=filename.tex
Create a Plain TeX file called filename.tex that shows the dvips
name and a font sample of every font that pkfix-helper used in the
output document.

Infrequently Used Options
-C filename, --cache=filename
Speed up TFM file processing by caching character metrics into file
filename. On some systems it takes a long time to read a TFM file,
spawn tftopl to convert it to PL format, and extract from the PL
data the metrics for each character. The first time --cache is
specified, pkfix-helper proceeds as normal then writes all of the
extracted character metrics to filename. On subsequent runs in
which --cache=filename is specified, pkfix-helper reads the
previously extracted metrics from filename, going through the
tftopl-based process only for TFM files that were not previously
encountered.

-q, --quiet
Instruct pkfix-helper to produce no output during its run except
for fatal error messages.

-1, --no-repeats
Prevent pkfix-helper from associating the same fontspec with more
than one dvips font name.

-i fontspec, --include=fontspec
Add fontspec to the list of font specifications against which
pkfix-helper compares every document font. (In contrast, --force
designates a font specification to use only for a specific document
font.) The --include option can be specified repeatedly on the
command line.

-x regexp, --exclude=regexp
Remove all font specifications matching regular expression regexp
from pkfix-helper's list of known fonts. The --exclude option can
be specified repeatedly on the command line.

-k fontspec, --keep=fontspec
Do not substitute a vector font for bitmapped font fontspec ("Fa",
"Fb", etc.). This is useful when converting documents that use
obscure bitmapped fonts for which there is no vector equivalent.
For example, it was somewhat common in the past to include graphics
such as university or corporate logos into a document by converting
the bitmapped image into a single-character font and using that
font in LaTeX. --keep prevents such fonts from being replaced.
The --keep option can be specified repeatedly on the command line.

-a, --any-scale
Allow any value to be used to scale a font when ""*"" is specified
as the scale factor. Normally, pkfix-helper considers only integer
multiples of 0.1 that are greater than or equal to 1.0 (i.e.,
fontname@1X, "@1.1X", "@1.2X", "@1.3X", etc.).

-s, --spp
Specify the number of font samples per page to print to the files
indicated using the --ps and --tex options. The default value, 25,
should work well in most circumstances.

DIAGNOSTICS
"Best match for name is rather poor"
The best font pkfix-helper found for dvips font name name has a
mismatch value greater than or equal to 1.0. (The mismatch value
is the sum of the squares of the difference between the character
widths of a document font and a potential replacement font.) Use
the --force option to designate an alternative replacement font or
scaling amount.

EXAMPLES
For the purpose of the following examples, assume that oldfile.ps is
the name of a PostScript file produced by an old version of dvips and
utilizing at least one bitmapped font. It's always worth verifying
that pkfix can't convert the file on its own:

$ pkfix oldfile.ps newfile.ps
PKFIX 1.3, 2005/02/25 - Copyright (c) 2001, 2005 by Heiko Oberdiek.
==> no fonts converted

(Alternatively pkfix may issue an error message such as "!!! Error:
Parse error (@start parameters)!".) Only when pkfix can't replace
bitmapped fonts with vector fonts is pkfix-helper needed. In its
simplest form, pkfix-helper takes the name of an input file (oldfile.ps
in this example) and the name of an output file (pkfix-oldfile.ps),
which will have the same contents as the input file but serve as
suitable input for pkfix:

$ pkfix-helper oldfile.ps pkfix-oldfile.ps
Reading oldfile.ps ... done.
Number of Type 3 fonts encountered: 10
Bitmapped fonts are typeset at 600 DPI.
Finding character widths ... done.
Reading TFM files ... done (103 TFMs in 193 scaling variations).
Matching fonts:
Processing Fi ... done (cmr10 @ 1X, mismatch=0.11683).
Processing Fa ... done (cmti10 @ 1X, mismatch=0.08892).
Processing Fb ... done (cmr8 @ 1X, mismatch=0.07133).
Processing Ff ... done (cmbx12 @ 1.2X, mismatch=0.02948).
Processing Fh ... done (cmtt10 @ 1X, mismatch=0.06895).
Processing Fd ... done (cmmi10 @ 1X, mismatch=0.03966).
Processing Fj ... done (cmbx12 @ 1X, mismatch=0.03972).
Processing Fe ... done (cmbx10 @ 1X, mismatch=0.00762).
Processing Fg ... done (cmsy10 @ 1X, mismatch=0.00875).
Processing Fc ... done (cmr6 @ 1X, mismatch=0.00284).

$ pkfix pkfix-oldfile.ps newfile.ps
PKFIX 1.3, 2005/02/25 - Copyright (c) 2001, 2005 by Heiko Oberdiek.
*** Font conversion: `cmti10' -> `CMTI10'.
*** Font conversion: `cmr8' -> `CMR8'.
*** Font conversion: `cmr6' -> `CMR6'.
*** Font conversion: `cmmi10' -> `CMMI10'.
*** Font conversion: `cmbx10' -> `CMBX10'.
*** Font conversion: `cmbx12' -> `CMBX12'.
*** Font conversion: `cmsy10' -> `CMSY10'.
*** Font conversion: `cmtt10' -> `CMTT10'.
*** Font conversion: `cmr10' -> `CMR10'.
*** Font conversion: `cmbx12' -> `CMBX12'.
*** Merging font `CMBX12' (2).
==> 10 converted fonts.
==> 1 merged font.

Although pkfix-helper tries to automate as much as possible the font-
detection process, some fonts will invariably be incorrectly
identified. The program outputs a warning message if it knows a match
is bad but the lack of a warning message does not necessarily indicate
that pkfix-helper did a good job. It is therefore strongly recommended
that the user produce "before" and "after" font sheets:

$ pkfix-helper -q oldfile.ps pkfix-oldfile.ps \
--ps=oldfonts.ps --tex=newfonts.tex

$ tex newfonts.tex
This is TeX, Version 3.14159 (Web2C 7.4.5)
(./newfonts.tex [1] )
Output written on newfonts.dvi (1 page, 1292 bytes).
Transcript written on newfonts.log.

$ dvips newfonts.dvi -o newfonts.ps
This is dvips(k) 5.92b Copyright 2002 Radical Eye Software (www.radicaleye.com)
' TeX output 2006.06.11:1636' -> newfonts.ps
<texc.pro><8r.enc><texps.pro>. <cmr6.pfb><cmsy10.pfb><cmbx10.pfb><cmbx12.pfb>
<cmmi10.pfb><cmtt10.pfb><cmr8.pfb><cmti10.pfb><cmr10.pfb>[1]

After running the preceding commands, oldfonts.ps shows samples of the
fonts in oldfile.ps and newfonts.ps shows samples of the replacement
fonts that pkfix-helper used to produce pkfix-oldfile.ps. Print
oldfonts.ps and newfonts.ps and compare them carefully for incorrect
fonts and sizes.

Suppose that the choice of "cmbx12 @ 1.2X" for font "Ff" looks wrong;
say the characters look taller in oldfonts.ps than in newfonts.ps.
This is where the trial-and-error stage begins. Let's hypothesize that
"cmb12" is a better match than "cmbx12" but we don't know how much to
scale the font. Fortunately, pkfix-helper allows "*" to be used as a
scaling factor to tell the program to automatically detect an optimal
scaling factor, even if doing so means choosing a nonstandard font
size:

$ pkfix-helper oldfile.ps pkfix-oldfile.ps --force="Ff=cmb12 @ *"
Reading oldfile.ps ... done.
Number of Type 3 fonts encountered: 10
Bitmapped fonts are typeset at 600 DPI.
Finding character widths ... done.
Reading TFM files ... failed.
pkfix-helper: Unable to process user-specified TFM file "cmb12"

Oops, it looks like we don't have a cmb12.tfm file on our system.
Let's try scaling up cmb10.tfm instead:

$ pkfix-helper oldfile.ps pkfix-oldfile.ps --force="Ff=cmb10 @ *"
Reading oldfile.ps ... done.
Number of Type 3 fonts encountered: 10
Bitmapped fonts are typeset at 600 DPI.
Finding character widths ... done.
Reading TFM files ... done (103 TFMs in 193 scaling variations).
Matching fonts:
Processing Fi ... done (cmr10 @ 1X, mismatch=0.11683).
Processing Fa ... done (cmti10 @ 1X, mismatch=0.08892).
Processing Fb ... done (cmr8 @ 1X, mismatch=0.07133).
Processing Ff ... done (cmb10 @ 1.5X, mismatch=0.00035).
Processing Fh ... done (cmtt10 @ 1X, mismatch=0.06895).
Processing Fd ... done (cmmi10 @ 1X, mismatch=0.03966).
Processing Fj ... done (cmbx12 @ 1X, mismatch=0.03972).
Processing Fe ... done (cmbx10 @ 1X, mismatch=0.00762).
Processing Fg ... done (cmsy10 @ 1X, mismatch=0.00875).
Processing Fc ... done (cmr6 @ 1X, mismatch=0.00284).

The match has definitely improved, although 15 pt. is certainly an odd
size for a font. Then again, many documents do use nonstandard sizes
so this may in fact be correct. The best way to verify is once again
to produce, print, and compare a pair of font samples and iterate until
all of the fonts look correct. Use one instance of --force for each
font you want to alter.

ENVIRONMENT
pkfix-helper honors the following environment variables:

GS The name of the Ghostscript interpreter (default: gs)

TFTOPL The name of a utility for converting .tfm files to .pl files
(default: tftopl)

BUGS
Even when pkfix-helper finds a perfect match (i.e., the correct font in
the correct size) the mismatch value is still typically nonzero. The
same error is probably what causes pkfix-helper sometimes to consider
the wrong font as being a better match than the correct font.
Suggestions for fixing these bugs are welcome.

RESTRICTIONS
pkfix-helper works only with PostScript files produced by dvips, not
with arbitrary PostScript files. The program has not been tested with
output from versions of dvips older than v5.490 (ca. 1992); output from
older versions may or may not work. Only bitmapped fonts loaded by
dvips can be analyzed, not bitmapped fonts loaded by embedded graphics.

pkfix-helper works by comparing character widths, not the actual
glyphs. Consequently, it is misled by sets of fonts with similar
character widths (at least for those characters used by a given
document). As an extreme example, all Computer Modern Teletype fonts
of a given design size (e.g., "cmtt10", "cmsltt10", and "cmitt10") use
exactly the same widths for all characters. Human assistance is
generally needed to guide pkfix-helper's font-matching procedures.

NOTES
Files produced using the --tex option are Plain TeX files and therefore
must be compiled with tex (or a variation such as pdftex, luatex,
etc.), not with latex.

SEE ALSO
pkfix(1), dvips(1), tex(1), gs(1)

PostScript Language Reference, Third Edition. Published by Addison-
Wesley, ISBN 0-201-37922-8,
<http://www.adobe.com/products/postscript/pdfs/PLRM.pdf>.

AUTHOR
Scott Pakin, scott+pkfh@pakin.org

This file may be distributed and/or modified under the conditions of
the LaTeX Project Public License, either version 1.3c of this license
or (at your option) any later version. The latest version of this
license is in <http://www.latex-project.org/lppl.txt> and version 1.3c
or later is part of all distributions of LaTeX version 2006/05/20 or
later.

v1.4 2011-06-11 PKFIX-HELPER(1)

pkfix-helper

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