1Xpdf
2====
3
4version 4.03
52021-jan-28
6
7The Xpdf software and documentation are
8copyright 1996-2021 Glyph & Cog, LLC.
9
10Email: xpdf@xpdfreader.com
11WWW: http://www.xpdfreader.com/
12
13The PDF data structures, operators, and specification are
14documented in ISO 32000-2:2020.
15
16
17What is Xpdf?
18-------------
19
20Xpdf is an open source viewer for Portable Document Format (PDF)
21files. (These are also sometimes also called 'Acrobat' files, from
22the name of Adobe's PDF software.) The Xpdf project also includes a
23PDF text extractor, PDF-to-PostScript converter, and various other
24utilities.
25
26The Xpdf viewer uses the Qt cross-platform GUI toolkit. The other
27command line utilties do not require Qt.
28
29
30License & Distribution
31----------------------
32
33Xpdf is licensed under the GNU General Public License (GPL), version 2
34or 3. This means that you can distribute derivatives of Xpdf under
35any of the following:
36 - GPL v2 only
37 - GPL v3 only
38 - GPL v2 or v3
39
40The Xpdf source package includes the text of both GPL versions:
41COPYING for GPL v2, COPYING3 for GPL v3.
42
43Please note that Xpdf is NOT licensed under "any later version" of the
44GPL, as I have no idea what those versions will look like.
45
46If you are redistributing unmodified copies of Xpdf (or any of the
47Xpdf tools) in binary form, you need to include all of the
48documentation: README, man pages (or help files), COPYING, and
49COPYING3.
50
51If you want to incorporate the Xpdf source code into another program
52(or create a modified version of Xpdf), and you are distributing that
53program, you have two options: release your program under the GPL (v2
54and/or v3), or purchase a commercial Xpdf source license.
55
56If you're interested in commercial licensing, please see the Glyph &
57Cog web site:
58
59 http://www.glyphandcog.com/
60
61
62Compatibility
63-------------
64
65Xpdf uses the Qt toolkit and runs on Linux, Windows, and OS X -- and
66probably other systems that have a Qt port.
67
68The non-GUI command line utilities (pdftops, pdftotext, pdftohtml,
69pdfinfo, pdffonts, pdfdetach, pdftoppm, pdftopng, and pdfimages) run
70on Linux, Windows, and OS X -- and should run on pretty much any
71system with a decent C++ compiler.
72
73If you compile Xpdf for a system not listed on the web page, please
74let me know. If you're willing to make your binary available by ftp
75or on the web, I'll be happy to add a link from the Xpdf web page. I
76have decided not to host any binaries I didn't compile myself (for
77disk space and support reasons).
78
79If you can't get Xpdf to compile on your system, send me email and
80I'll try to help.
81
82
83Getting Xpdf
84------------
85
86The latest version is available from:
87
88 http://www.xpdfreader.com/
89
90Source code and several precompiled executables are available.
91
92Announcements of new versions are posted to comp.text.pdf and emailed
93to a list of people. If you'd like to receive email notification of
94new versions, just let me know.
95
96
97Running Xpdf
98------------
99
100To run xpdf, simply type:
101
102 xpdf file.pdf
103
104To generate a PostScript file, run pdftops:
105
106 pdftops file.pdf
107
108To generate a plain text file, run pdftotext:
109
110 pdftotext file.pdf
111
112There are several additional utilities (which are fully described in
113their man pages):
114
115 pdftohtml -- converts a PDF file to HTML
116 pdfinfo -- dumps a PDF file's Info dictionary (plus some other
117 useful information)
118 pdffonts -- lists the fonts used in a PDF file along with various
119 information for each font
120 pdfdetach -- lists or extracts embedded files (attachments) from a
121 PDF file
122 pdftoppm -- converts a PDF file to a series of PPM/PGM/PBM-format
123 bitmaps
124 pdftopng -- converts a PDF file to a series of PNG image files
125 pdfimages -- extracts the images from a PDF file
126
127Command line options and many other details are described in the man
128pages: xpdf(1), etc.
129
130All of these utilities read an optional configuration file: see the
131xpdfrc(5) man page.
132
133
134Compiling Xpdf
135--------------
136
137See the separate file, INSTALL.
138
139
140Bugs
141----
142
143If you find a bug in Xpdf, i.e., if it prints an error message,
144crashes, or incorrectly displays a document, and you don't see that
145bug listed here, please send me email, with a pointer (URL, ftp site,
146etc.) to the PDF file.
147
148
149Third-Party Libraries
150---------------------
151
152Xpdf uses the following libraries:
153* FreeType [http://www.freetype.org/]
154* libpng [http://www.libpng.com/pub/png/libpng.html] (used by pdftohtml
155 and pdftopng)
156* zlib [http://zlib.net/] (used by pdftohtml)
157
158
159Acknowledgments
160---------------
161
162Thanks to:
163
164* Patrick Voigt for help with the remote server code.
165* Patrick Moreau, Martin P.J. Zinser, and David Mathog for the VMS
166 port.
167* David Boldt and Rick Rodgers for sample man pages.
168* Brendan Miller for the icon idea.
169* Olly Betts for help testing pdftotext.
170* Peter Ganten for the OS/2 port.
171* Michael Richmond for the Win32 port of pdftops and pdftotext and the
172 xpdf/cygwin/XFree86 build instructions.
173* Frank M. Siegert for improvements in the PostScript code.
174* Leo Smiers for the decryption patches.
175* Rainer Menzner for creating t1lib, and for helping me adapt it to
176 xpdf.
177* Pine Tree Systems A/S for funding the OPI and EPS support in
178 pdftops.
179* Easy Software Products for funding several improvements to the
180 PostScript output code.
181* Tom Kacvinsky for help with FreeType and for being my interface to
182 the FreeType team.
183* Theppitak Karoonboonyanan for help with Thai support.
184* Leonard Rosenthol for help and contributions on a bunch of things.
185* Alexandros Diamantidis and Maria Adaloglou for help with Greek
186 support.
187* Lawrence Lai for help with the CJK Unicode maps.
188
189Various people have contributed modifications made for use by the
190pdftex project:
191
192* Han The Thanh
193* Martin Schr�der of ArtCom GmbH
194
195
196References
197----------
198
199Adobe Systems Inc., _PostScript Language Reference_, 3rd ed.
200Addison-Wesley, 1999, ISBN 0-201-37922-8.
201[The official PostScript manual.]
202
203Adobe Systems, Inc., _The Type 42 Font Format Specification_,
204Adobe Developer Support Technical Specification #5012. 1998.
205http://partners.adobe.com/asn/developer/pdfs/tn/5012.Type42_Spec.pdf
206[Type 42 is the format used to embed TrueType fonts in PostScript
207files.]
208
209Adobe Systems, Inc., _Adobe CMap and CIDFont Files Specification_,
210Adobe Developer Support Technical Specification #5014. 1995.
211http://www.adobe.com/supportservice/devrelations/PDFS/TN/5014.CIDFont_Spec.pdf
212[CMap file format needed for Japanese and Chinese font support.]
213
214Adobe Systems, Inc., _Adobe-Japan1-4 Character Collection for
215CID-Keyed Fonts_, Adobe Developer Support Technical Note #5078.
2162000.
217http://partners.adobe.com/asn/developer/PDFS/TN/5078.CID_Glyph.pdf
218[The Adobe Japanese character set.]
219
220Adobe Systems, Inc., _Adobe-GB1-4 Character Collection for
221CID-Keyed Fonts_, Adobe Developer Support Technical Note #5079.
2222000.
223http://partners.adobe.com/asn/developer/pdfs/tn/5079.Adobe-GB1-4.pdf
224[The Adobe Chinese GB (simplified) character set.]
225
226Adobe Systems, Inc., _Adobe-CNS1-3 Character Collection for
227CID-Keyed Fonts_, Adobe Developer Support Technical Note #5080.
2282000.
229http://partners.adobe.com/asn/developer/PDFS/TN/5080.CNS_CharColl.pdf
230[The Adobe Chinese CNS (traditional) character set.]
231
232Adobe Systems Inc., _Supporting the DCT Filters in PostScript Level
2332_, Adobe Developer Support Technical Note #5116. 1992.
234http://www.adobe.com/supportservice/devrelations/PDFS/TN/5116.PS2_DCT.PDF
235[Description of the DCTDecode filter parameters.]
236
237Adobe Systems Inc., _Open Prepress Interface (OPI) Specification -
238Version 2.0_, Adobe Developer Support Technical Note #5660. 2000.
239http://partners.adobe.com/asn/developer/PDFS/TN/5660.OPI_2.0.pdf
240
241Adobe Systems Inc., CMap files.
242ftp://ftp.oreilly.com/pub/examples/nutshell/cjkv/adobe/
243[The actual CMap files for the 16-bit CJK encodings.]
244
245Adobe Systems Inc., Unicode glyph lists.
246http://partners.adobe.com/asn/developer/type/unicodegn.html
247http://partners.adobe.com/asn/developer/type/glyphlist.txt
248http://partners.adobe.com/asn/developer/type/corporateuse.txt
249http://partners.adobe.com/asn/developer/type/zapfdingbats.txt
250[Mappings between character names to Unicode.]
251
252Adobe Systems Inc., OpenType Specification v. 1.4.
253http://partners.adobe.com/public/developer/opentype/index_spec.html
254[The OpenType font format spec.]
255
256Aldus Corp., _OPI: Open Prepress Interface Specification 1.3_. 1993.
257http://partners.adobe.com/asn/developer/PDFS/TN/OPI_13.pdf
258
259Anonymous, RC4 source code.
260ftp://ftp.ox.ac.uk/pub/crypto/misc/rc4.tar.gz
261ftp://idea.sec.dsi.unimi.it/pub/crypt/code/rc4.tar.gz
262[This is the algorithm used to encrypt PDF files.]
263
264T. Boutell, et al., "PNG (Portable Network Graphics) Specification,
265Version 1.0". RFC 2083.
266[PDF uses the PNG filter algorithms.]
267
268CCITT, "Information Technology - Digital Compression and Coding of
269Continuous-tone Still Images - Requirements and Guidelines", CCITT
270Recommendation T.81.
271http://www.w3.org/Graphics/JPEG/
272[The official JPEG spec.]
273
274A. Chernov, "Registration of a Cyrillic Character Set". RFC 1489.
275[Documentation for the KOI8-R Cyrillic encoding.]
276
277Roman Czyborra, "The ISO 8859 Alphabet Soup".
278http://czyborra.com/charsets/iso8859.html
279[Documentation on the various ISO 859 encodings.]
280
281L. Peter Deutsch, "ZLIB Compressed Data Format Specification version
2823.3". RFC 1950.
283[Information on the general format used in FlateDecode streams.]
284
285L. Peter Deutsch, "DEFLATE Compressed Data Format Specification
286version 1.3". RFC 1951.
287[The definition of the compression algorithm used in FlateDecode
288streams.]
289
290Morris Dworkin, "Recommendation for Block Cipher Modes of Operation",
291National Institute of Standards, NIST Special Publication 800-38A,
2922001.
293[The cipher block chaining (CBC) mode used with AES in PDF files.]
294
295Federal Information Processing Standards Publication 197 (FIPS PUBS
296197), "Advanced Encryption Standard (AES)", November 26, 2001.
297[AES encryption, used in PDF 1.6.]
298
299Jim Flowers, "X Logical Font Description Conventions", Version 1.5, X
300Consortium Standard, X Version 11, Release 6.1.
301ftp://ftp.x.org/pub/R6.1/xc/doc/hardcopy/XLFD/xlfd.PS.Z
302[The official specification of X font descriptors, including font
303transformation matrices.]
304
305Foley, van Dam, Feiner, and Hughes, _Computer Graphics: Principles and
306Practice_, 2nd ed. Addison-Wesley, 1990, ISBN 0-201-12110-7.
307[Colorspace conversion functions, Bezier spline math.]
308
309Robert L. Hummel, _Programmer's Technical Reference: Data and Fax
310Communications_. Ziff-Davis Press, 1993, ISBN 1-56276-077-7.
311[CCITT Group 3 and 4 fax decoding.]
312
313ISO/IEC, _Information technology -- Lossy/lossless coding of bi-level
314images_. ISO/IEC 14492, First edition (2001-12-15).
315http://webstore.ansi.org/
316[The official JBIG2 standard. The final draft of this spec is
317available from http://www.jpeg.org/jbighomepage.html.]
318
319ISO/IEC, _Information technology -- JPEG 2000 image coding system --
320Part 1: Core coding system_. ISO/IEC 15444-1, First edition
321(2000-12-15).
322http://webstore.ansi.org/
323[The official JPEG 2000 standard. The final committee draft of this
324spec is available from http://www.jpeg.org/JPEG2000.html, but there
325were changes made to the bitstream format between that draft and the
326published spec.]
327
328ISO, International Standard -- Document Management - Portable document
329format - Part 2: PDF 2.0. ISO 32000-2:2020.
330[The specification for PDF version 2.0.]
331
332ITU, "Standardization of Group 3 facsimile terminals for document
333transmission", ITU-T Recommendation T.4, 1999.
334ITU, "Facsimile coding schemes and coding control functions for Group 4
335facsimile apparatus", ITU-T Recommendation T.6, 1993.
336http://www.itu.int/
337[The official Group 3 and 4 fax standards - used by the CCITTFaxDecode
338stream, as well as the JBIG2Decode stream.]
339
340B. Kaliski, "PKCS #5: Password-Based Cryptography Specification,
341Version 2.0". RFC 2898.
342[Defines the padding scheme used with AES encryption in PDF files.]
343
344Christoph Loeffler, Adriaan Ligtenberg, George S. Moschytz, "Practical
345Fast 1-D DCT Algorithms with 11 Multiplications". IEEE Intl. Conf. on
346Acoustics, Speech & Signal Processing, 1989, 988-991.
347[The fast IDCT algorithm used in the DCTDecode filter.]
348
349Microsoft, _TrueType 1.0 Font Files_, rev. 1.66. 1995.
350http://www.microsoft.com/typography/tt/tt.htm
351[The TrueType font spec (in MS Word format, naturally).]
352
353V. Ostromoukhov, R.D. Hersch, "Stochastic Clustered-Dot Dithering",
354Conf. Color Imaging: Device-Independent Color, Color Hardcopy, and
355Graphic Arts IV, 1999, SPIE Vol. 3648, 496-505.
356http://diwww.epfl.ch/w3lsp/publications/colour/scd.html
357[The stochastic dithering algorithm used in Xpdf.]
358
359P. Peterlin, "ISO 8859-2 (Latin 2) Resources".
360http://sizif.mf.uni-lj.si/linux/cee/iso8859-2.html
361[This is a web page with all sorts of useful Latin-2 character set and
362font information.]
363
364Charles Poynton, "Color FAQ".
365http://www.inforamp.net/~poynton/ColorFAQ.html
366[The mapping from the CIE 1931 (XYZ) color space to RGB.]
367
368R. Rivest, "The MD5 Message-Digest Algorithm". RFC 1321.
369[MD5 is used in PDF document encryption.]
370
371Thai Industrial Standard, "Standard for Thai Character Codes for
372Computers", TIS-620-2533 (1990).
373http://www.nectec.or.th/it-standards/std620/std620.htm
374[The TIS-620 Thai encoding.]
375
376Unicode Consortium, "Unicode Home Page".
377http://www.unicode.org/
378[Online copy of the Unicode spec.]
379
380W3C Recommendation, "PNG (Portable Network Graphics) Specification
381Version 1.0".
382http://www.w3.org/Graphics/PNG/
383[Defines the PNG image predictor.]
384
385Gregory K. Wallace, "The JPEG Still Picture Compression Standard".
386ftp://ftp.uu.net/graphics/jpeg/wallace.ps.gz
387[Good description of the JPEG standard. Also published in CACM, April
3881991, and submitted to IEEE Transactions on Consumer Electronics.]
389
390F. Yergeau, "UTF-8, a transformation format of ISO 10646". RFC 2279.
391[A commonly used Unicode encoding.]
392
