Xpdf ==== version 0.93 2001-oct-25 The Xpdf software and documentation are copyright 1996-2001 Derek B. Noonburg. Email: derekn@foolabs.com WWW: http://www.foolabs.com/xpdf/ The PDF data structures, operators, and specification are copyright 1995 Adobe Systems Inc. What is Xpdf? ------------- Xpdf is a viewer for Portable Document Format (PDF) files. (These are also sometimes also called 'Acrobat' files, from the name of Adobe's PDF software.) Xpdf runs under the X Window System on UNIX, VMS, and OS/2. The non-X components of the package (pdftops, pdftotext, etc.) also run on Win32 systems and should run on pretty much any system with a decent C++ compiler. Xpdf is designed to be small and efficient. It can use Type 1, TrueType, or standard X fonts. Distribution ------------ Xpdf is licensed under the GNU General Public License (GPL), version 2. In my opinion, the GPL is a convoluted, confusing, ambiguous mess. But it's also pervasive, and I'm sick of arguing. And even if it is confusing, the basic idea is good. In order to cut down on the confusion a little bit, here are some informal clarifications: - I don't mind if you redistribute Xpdf in source and/or binary form, as long as you include all of the documentation: README, man pages (or help files), and COPYING. (Note that the README file contains a pointer to a web page with the source code.) - Selling a CD-ROM that contains Xpdf is fine with me, as long as it includes the documentation. I wouldn't mind receiving a sample copy, but it's not necessary. - If you make useful changes to Xpdf, please make the source code available -- post it on a web site, email it to me, whatever. If you're interested in commercial licensing, please contact me by email: derekn@foolabs.com . Compatibility ------------- Xpdf is developed and tested on a Linux 2.2 x86 system. In addition, it has been compiled by others on Solaris, AIX, HP-UX, SCO UnixWare, Digital Unix, Irix, and numerous other Unix implementations, as well as VMS and OS/2. It should work on pretty much any system which runs X11 and has Unix-like libraries. You'll need ANSI C++ and C compilers to compile it. The non-X components of Xpdf (pdftops, pdftotext, pdfinfo, pdfimages) can also be compiled on Win32 systems. See the Xpdf web page for details. If you compile Xpdf for a system not listed on the web page, please let me know. If you're willing to make your binary available by ftp or on the web, I'll be happy to add a link from the Xpdf web page. I have decided not to host any binaries I didn't compile myself (for disk space and support reasons). If you can't get Xpdf to compile on your system, send me email and I'll try to help. Xpdf has been ported to the Acorn, Amiga, BeOS, and EPOC. See the Xpdf web page for links. Getting Xpdf ------------ The latest version is available from: http://www.foolabs.com/xpdf/ or: ftp://ftp.foolabs.com/pub/xpdf/ Source code and several precompiled executables are available. Announcements of new versions are posted to several newsgroups (comp.text.pdf, comp.os.linux.announce, and others) and emailed to a list of people. If you'd like to receive email notification of new versions, just let me know. Running Xpdf ------------ To run xpdf, simply type: xpdf file.pdf To generate a PostScript file, hit the "print" button in xpdf, or run pdftops: pdftops file.pdf To generate a plain text file, run pdftotext: pdftotext file.pdf There are three additional utilities (which are fully described in their man pages): pdfinfo -- dumps a PDF file's Info dictionary (plus some other useful information) pdftopbm -- converts a PDF file to a series of PBM-format bitmaps pdfimages -- extracts the images from a PDF file Command line options and many other details are described in the man pages (xpdf.1, etc.) and the VMS help files (xpdf.hlp, etc.). Fonts ----- Xpdf uses X server fonts. It requires the following fonts: * Courier: medium-r, bold-r, medium-o, and bold-o * Helvetica: medium-r, bold-r, medium-o, and bold-o * Times: medium-r, bold-r, medium-i, and bold-i * Symbol: medium-r * Zapf Dingbats: medium-r Most X installations should already have all of these fonts, except Zapf Dingbats. You can install a Type 1 Zapf Dingbats font -- see the mkfontdir(1) man page for details. Use this font descriptor in your fonts.scale file: -itc-zapfdingbats-medium-r-normal--0-0-0-0-p-0-adobe-fontspecific You can get a Type 1 font file from the ghostscript 4.x distribution (look for d050000l.pfb). X servers, starting at R5, support font scaling. Xpdf will automatically take advantage of this. There are two types of scaling. The first type uses standard bitmap fonts: if a font doesn't exist in the requested size, the server will scale the bitmapped characters. This is reasonably fast, and the results are readable but not very pretty. X servers can also handle true scalable, e.g., Type 1, fonts. (See the mkfontdir(1) man page for details on setting these up.) Scalable fonts are slower, especially since PDF documents tend to use lots of fonts, but they look much nicer. Some X servers also support font rotation. Xpdf will use this feature if available. For Japanese support, you will need a Japanese font of the form: -*-fixed-medium-r-normal-*-NN-*-*-*-*-*-jisx0208.1983-0 and an X server that can handle 16-bit fonts. You can also set this font using the xpdf.japaneseFont resource. For Chinese GB (simplified Chinese) support, you will need a font of the form: -*-fangsong ti-medium-r-normal-*-%s-*-*-*-*-*-gb2312.1980-0 You can replace this font using the xpdf.chineseGBFont resource. For Chinese CNS (traditional Chinese) support, you will need a font of the form: -*-fixed-medium-r-normal--*-%s-*-*-*-*-big5-0 You can replace this font using the xpdf.chineseCNSFont resource. If compiled with t1lib support, xpdf will use t1lib to render embedded Type 1 and Type 1C fonts. In addition, xpdf can be configured to use t1lib for the base 14 fonts and for substituted fonts. To enable this feature, you must set an X resource for each Type 1 font file. For example: xpdf.t1TimesRoman: /usr/local/fonts/Times-Roman.pfa xpdf.t1TimesItalic: /usr/local/fonts/Times-Italic.pfa xpdf.t1TimesBold: /usr/local/fonts/Times-Bold.pfa xpdf.t1TimesBoldItalic: /usr/local/fonts/Times-BoldItalic.pfa xpdf.t1Helvetica: /usr/local/fonts/Helvetica.pfa xpdf.t1HelveticaOblique: /usr/local/fonts/Helvetica-Oblique.pfa xpdf.t1HelveticaBold: /usr/local/fonts/Helvetica-Bold.pfa xpdf.t1HelveticaBoldOblique: /usr/local/fonts/Helvetica-BoldOblique.pfa xpdf.t1Courier: /usr/local/fonts/Courier.pfa xpdf.t1CourierOblique: /usr/local/fonts/Courier-Oblique.pfa xpdf.t1CourierBold: /usr/local/fonts/Courier-Bold.pfa xpdf.t1CourierBoldOblique: /usr/local/fonts/Courier-BoldOblique.pfa xpdf.t1Symbol: /usr/local/fonts/Symbol.pfa xpdf.t1ZapfDingbats: /usr/local/fonts/ZapfDingbats.pfa Ghostscript comes with a set of free, high-quality Type 1 fonts, donated by URW++ Design and Development Incorporated. The xpdf X resources needed for these fonts are: xpdf.t1TimesRoman: /usr/ghostscript/fonts/n021003l.pfb xpdf.t1TimesItalic: /usr/ghostscript/fonts/n021023l.pfb xpdf.t1TimesBold: /usr/ghostscript/fonts/n021004l.pfb xpdf.t1TimesBoldItalic: /usr/ghostscript/fonts/n021024l.pfb xpdf.t1Helvetica: /usr/ghostscript/fonts/n019003l.pfb xpdf.t1HelveticaOblique: /usr/ghostscript/fonts/n019023l.pfb xpdf.t1HelveticaBold: /usr/ghostscript/fonts/n019004l.pfb xpdf.t1HelveticaBoldOblique: /usr/ghostscript/fonts/n019024l.pfb xpdf.t1Courier: /usr/ghostscript/fonts/n022003l.pfb xpdf.t1CourierOblique: /usr/ghostscript/fonts/n022023l.pfb xpdf.t1CourierBold: /usr/ghostscript/fonts/n022004l.pfb xpdf.t1CourierBoldOblique: /usr/ghostscript/fonts/n022024l.pfb xpdf.t1Symbol: /usr/ghostscript/fonts/s050000l.pfb xpdf.t1ZapfDingbats: /usr/ghostscript/fonts/d050000l.pfb You will obviously need to replace '/usr/ghostscript/fonts' with the appropriate path on your system. The Unisys LZW Patent --------------------- Nearly all PDF files include data which has been compressed with the LZW compression algorithm. Unfortunately, LZW is covered by a software patent which is owned by Unisys Corporation. Unisys refuses to license this patent for PDF-related use in software such as Xpdf which is released for free and which may be freely redistributed. (This is same algorithm which is used by GIF. However, Unisys is not doing licensing for free PDF viwers in the same way as for free GIF viewers.) As a workaround, Xpdf converts PDF-format LZW data to compress-format LZW data. (The standard UNIX compress utility also uses LZW, but with a slightly different file format.) This conversion does *not* decompress the data; it simply converts it to a different file format. Xpdf then calls uncompress to actually decompress the data. I have been told by several notable people that the LZW patent covers compression only, and does not cover decompression. This seems pretty fuzzy to me, so I'm going to stick with my workaround, at least for now. For Unisys's slant on things (mostly regarding GIF), see and . These pages mention an email address for feedback. Compiling Xpdf -------------- See the separate file, INSTALL. Bugs ---- Type 3 fonts are still not well supported by Xpdf. If you find a bug in Xpdf, i.e., if it prints an error message, crashes, or incorrectly displays a document, and you don't see that bug listed here, please send me email, with a pointer (URL, ftp site, etc.) to the PDF file. Acknowledgments --------------- Thanks to: * Patrick Voigt for help with the remote server code. * Patrick Moreau, Martin P.J. Zinser, and David Mathog for the VMS port. * David Boldt and Rick Rodgers for sample man pages. * Brendan Miller for the icon idea. * Olly Betts for help testing pdftotext. * Peter Ganten for the OS/2 port. * Michael Richmond for the Win32 port of pdftops and pdftotext. * Frank M. Siegert for improvements in the PostScript code. * Leo Smiers for the decryption patches. * Rainer Menzner for creating t1lib, and for helping me adapt it to xpdf. * Pine Tree Systems A/S for funding the OPI and EPS support in pdftops. References ---------- Adobe Systems Inc., _PDF Reference_, 2nd ed. Addison-Wesley, 2000, ISBN 0-201-61588-6. [The printed manual for PDF version 1.3.] Adobe Systems Inc., _Portable Document Format: Changes from Version 1.3 to 1.4_, Adobe Developer Support Technical Note #5409. June 11, 2001. http://partners.adobe.com/asn/developer/acrosdk/docs/filefmtspecs/PDF14Deltas.pdf [Updates for PDF 1.4.] Adobe Systems Inc., _PostScript Language Reference_, 3rd ed. Addison-Wesley, 1999, ISBN 0-201-37922-8. [The official PostScript manual.] Adobe Systems, Inc., _The Type 42 Font Format Specification_, Adobe Developer Support Technical Specification #5012. 1998. http://partners.adobe.com/asn/developer/pdfs/tn/5012.Type42_Spec.pdf [Type 42 is the format used to embed TrueType fonts in PostScript files.] Adobe Systems, Inc., _Adobe CMap and CIDFont Files Specification_, Adobe Developer Support Technical Specification #5014. 1995. http://www.adobe.com/supportservice/devrelations/PDFS/TN/5014.CIDFont_Spec.pdf [CMap file format needed for Japanese and Chinese font support.] Adobe Systems, Inc., _Adobe-Japan1-2 Character Collection for CID-Keyed Fonts_, Adobe Developer Support Technical Note #5078. 1994. http://partners.adobe.com/asn/developer/PDFS/TN/5078.CID_Glyph.pdf [The Adobe Japanese character set.] Adobe Systems, Inc., _Adobe-GB1-3 Character Collection for CID-Keyed Fonts_, Adobe Developer Support Technical Note #5079. 1998. http://partners.adobe.com/asn/developer/PDFS/TN/5079.GB_CharColl.pdf [The Adobe Chinese GB character set.] Adobe Systems, Inc., _Adobe-CNS1-3 Character Collection for CID-Keyed Fonts_, Adobe Developer Support Technical Note #5080. 2000. http://partners.adobe.com/asn/developer/PDFS/TN/5080.CNS_CharColl.pdf [The Adobe Chinese CNS character set.] Adobe Systems Inc., _Supporting the DCT Filters in PostScript Level 2_, Adobe Developer Support Technical Note #5116. 1992. http://www.adobe.com/supportservice/devrelations/PDFS/TN/5116.PS2_DCT.PDF [Description of the DCTDecode filter parameters.] Adobe Systems Inc., _Open Prepress Interface (OPI) Specification - Version 2.0_, Adobe Developer Support Technical Note #5660. 2000. http://partners.adobe.com/asn/developer/PDFS/TN/5660.OPI_2.0.pdf Adobe Systems Inc., CMap files. ftp://ftp.oreilly.com/pub/examples/nutshell/cjkv/adobe/ [The actual CMap files for the 16-bit CJK encodings.] Aldus Corp., _OPI: Open Prepress Interface Specification 1.3_. 1993. http://partners.adobe.com/asn/developer/PDFS/TN/OPI_13.pdf Anonymous, RC4 source code. ftp://ftp.ox.ac.uk/pub/crypto/misc/rc4.tar.gz ftp://idea.sec.dsi.unimi.it/pub/crypt/code/rc4.tar.gz [This is the algorithm used to encrypt PDF files.] CCITT, _Blue Book_, Volume VII Fascicle 3: "Terminal Equipment and Protocols for Telematic Services", Recommendations T.4 and T.6. ftp://ftp.uu.net/doc/standards/ccitt/1988/7_3_01.ps ftp://ftp.uu.net/doc/standards/ccitt/1988/7_3_02.ps [The official Group 3 and 4 fax standards. The online copies are unfortunately misformatted.] L. Peter Deutsch, "ZLIB Compressed Data Format Specification version 3.3". RFC 1950. [Information on the general format used in FlateDecode streams.] L. Peter Deutsch, "DEFLATE Compressed Data Format Specification version 1.3". RFC 1951. [The definition of the compression algorithm used in FlateDecode streams.] Jim Flowers, "X Logical Font Description Conventions", Version 1.5, X Consortium Standard, X Version 11, Release 6.1. ftp://ftp.x.org/pub/R6.1/xc/doc/hardcopy/XLFD/xlfd.PS.Z [The official specification of X font descriptors, including font transformation matrices.] Foley, van Dam, Feiner, and Hughes, _Computer Graphics: Principles and Practice_, 2nd ed. Addison-Wesley, 1990, ISBN 0-201-12110-7. [Colorspace conversion functions, Bezier spline math.] Robert L. Hummel, _Programmer's Technical Reference: Data and Fax Communications_. Ziff-Davis Press, 1993, ISBN 1-56276-077-7. [CCITT Group 3 and 4 fax decoding.] Christoph Loeffler, Adriaan Ligtenberg, George S. Moschytz, "Practical Fast 1-D DCT Algorithms with 11 Multiplications". IEEE Intl. Conf. on Acoustics, Speech & Signal Processing, 1989, 988-991. [The fast IDCT algorithm used in the DCTDecode filter.] Microsoft, _TyueType 1.0 Font Files_, rev. 1.66. 1995. http://www.microsoft.com/typography/tt/tt.htm [The TrueType font spec (in MS Word format, naturally).] Charles Poynton, "Color FAQ". http://www.inforamp.net/~poynton/ColorFAQ.html [The mapping from the CIE 1931 (XYZ) color space to RGB.] R. Rivest, "The MD5 Message-Digest Algorithm". RFC 1321. [MD5 is used in PDF document encryption.] Gregory K. Wallace, "The JPEG Still Picture Compression Standard". ftp://ftp.uu.net/graphics/jpeg/wallace.ps.gz [Good description of the JPEG standard. Also published in CACM, April 1991, and submitted to IEEE Transactions on Consumer Electronics.] W3C Recommendation, "PNG (Portable Network Graphics) Specification Version 1.0". http://www.w3.org/Graphics/PNG/ [Defines the PNG image predictor.] "ISO 8859-2 (Latin 2) Resources". http://sizif.mf.uni-lj.si/linux/cee/iso8859-2.html [This is a web page with all sorts of useful Latin-2 character set and font information.]