INSTALLATION INSTRUCTIONS for the Independent JPEG Group's JPEG software Copyright (C) 1991-1998, Thomas G. Lane.This file is part of the Independent JPEG Group's software.For conditions of distribution and use, see the accompanying README file.  This file explains how to configure and install the IJG software.  We havetried to make this software extremely portable and flexible, so that it can beadapted to almost any environment.  The downside of this decision is that theinstallation process is complicated.  We have provided shortcuts to simplifythe task on common systems.  But in any case, you will need at least a littlefamiliarity with C programming and program build procedures for your system. If you are only using this software as part of a larger program, the largerprogram's installation procedure may take care of configuring the IJG code.For example, Ghostscript's installation script will configure the IJG code.You don't need to read this file if you just want to compile Ghostscript. If you are on a Unix machine, you may not need to read this file at all.Try doing	./configure	make	make testIf that doesn't complain, do	make install(better do "make -n install" first to see if the makefile will put the fileswhere you want them).  Read further if you run into snags or want to customizethe code for your system.  TABLE OF CONTENTS----------------- Before you startConfiguring the software:	using the automatic "configure" script	using one of the supplied jconfig and makefile files	by handBuilding the softwareTesting the softwareInstalling the softwareOptional stuffOptimizationHints for specific systems  BEFORE YOU START================ Before installing the software you must unpack the distributed source code.Since you are reading this file, you have probably already succeeded in thistask.  However, there is a potential for error if you needed to convert thefiles to the local standard text file format (for example, if you are onMS-DOS you may have converted LF end-of-line to CR/LF).  You must applysuch conversion to all the files EXCEPT those whose names begin with "test".The test files contain binary data; if you change them in any way then theself-test will give bad results. Please check the last section of this file to see if there are hints for thespecific machine or compiler you are using.  CONFIGURING THE SOFTWARE======================== To configure the IJG code for your system, you need to create two files:  * jconfig.h: contains values for system-dependent #define symbols.  * Makefile: controls the compilation process.(On a non-Unix machine, you may create "project files" or some othersubstitute for a Makefile.  jconfig.h is needed in any environment.) We provide three different ways to generate these files:  * On a Unix system, you can just run the "configure" script.  * We provide sample jconfig files and makefiles for popular machines;    if your machine matches one of the samples, just copy the right sample    files to jconfig.h and Makefile.  * If all else fails, read the instructions below and make your own files.  Configuring the software using the automatic "configure" script--------------------------------------------------------------- If you are on a Unix machine, you can just type	./configureand let the configure script construct appropriate configuration files.If you're using "csh" on an old version of System V, you might need to type	sh configureinstead to prevent csh from trying to execute configure itself.Expect configure to run for a few minutes, particularly on slower machines;it works by compiling a series of test programs. Configure was created with GNU Autoconf and it follows the usual conventionsfor GNU configure scripts.  It makes a few assumptions that you may want tooverride.  You can do this by providing optional switches to configure: * If you want to build libjpeg as a shared library, say	./configure --enable-sharedTo get both shared and static libraries, say	./configure --enable-shared --enable-staticNote that these switches invoke GNU libtool to take care of system-dependentshared library building methods.  If things don't work this way, please tryrunning configure without either switch; that should build a static librarywithout using libtool.  If that works, your problem is probably with libtoolnot with the IJG code.  libtool is fairly new and doesn't support all flavorsof Unix yet.  (You might be able to find a newer version of libtool than theone included with libjpeg; see ftp.gnu.org.  Report libtool problems tobug-libtool@gnu.org.) * Configure will use gcc (GNU C compiler) if it's available, otherwise cc.To force a particular compiler to be selected, use the CC option, for example	./configure CC='cc'The same method can be used to include any unusual compiler switches.For example, on HP-UX you probably want to say	./configure CC='cc -Aa'to get HP's compiler to run in ANSI mode. * The default CFLAGS setting is "-O" for non-gcc compilers, "-O2" for gcc.You can override this by saying, for example,	./configure CFLAGS='-g'if you want to compile with debugging support. * Configure will set up the makefile so that "make install" will install filesinto /usr/local/bin, /usr/local/man, etc.  You can specify an installationprefix other than "/usr/local" by giving configure the option "--prefix=PATH". * If you don't have a lot of swap space, you may need to enable the IJGsoftware's internal virtual memory mechanism.  To do this, give the option"--enable-maxmem=N" where N is the default maxmemory limit in megabytes.This is discussed in more detail under "Selecting a memory manager", below.You probably don't need to worry about this on reasonably-sized Unix machines,unless you plan to process very large images. Configure has some other features that are useful if you are cross-compilingor working in a network of multiple machine types; but if you need thosefeatures, you probably already know how to use them.  Configuring the software using one of the supplied jconfig and makefile files----------------------------------------------------------------------------- If you have one of these systems, you can just use the provided configurationfiles: Makefile	jconfig file	System and/or compiler makefile.manx	jconfig.manx	Amiga, Manx Aztec Cmakefile.sas	jconfig.sas	Amiga, SAS Cmakeproj.mac	jconfig.mac	Apple Macintosh, Metrowerks CodeWarriormak*jpeg.st	jconfig.st	Atari ST/STE/TT, Pure C or Turbo Cmakefile.bcc	jconfig.bcc	MS-DOS or OS/2, Borland Cmakefile.dj	jconfig.dj	MS-DOS, DJGPP (Delorie's port of GNU C)makefile.mc6	jconfig.mc6	MS-DOS, Microsoft C (16-bit only)makefile.wat	jconfig.wat	MS-DOS, OS/2, or Windows NT, Watcom Cmakefile.vc	jconfig.vc	Windows NT/95, MS Visual C++make*.ds	jconfig.vc	Windows NT/95, MS Developer Studiomakefile.mms	jconfig.vms	Digital VMS, with MMS softwaremakefile.vms	jconfig.vms	Digital VMS, without MMS software Copy the proper jconfig file to jconfig.h and the makefile to Makefile (orwhatever your system uses as the standard makefile name).  For more info seethe appropriate system-specific hints section near the end of this file.  Configuring the software by hand-------------------------------- First, generate a jconfig.h file.  If you are moderately familiar with C,the comments in jconfig.doc should be enough information to do this; justcopy jconfig.doc to jconfig.h and edit it appropriately.  Otherwise, you mayprefer to use the ckconfig.c program.  You will need to compile and executeckconfig.c by hand --- we hope you know at least enough to do that.ckconfig.c may not compile the first try (in fact, the whole idea is for itto fail if anything is going to).  If you get compile errors, fix them byediting ckconfig.c according to the directions given in ckconfig.c.  Onceyou get it to run, it will write a suitable jconfig.h file, and will alsoprint out some advice about which makefile to use. You may also want to look at the canned jconfig files, if there is one for asystem similar to yours. Second, select a makefile and copy it to Makefile (or whatever your systemuses as the standard makefile name).  The most generic makefiles we provideare	makefile.ansi:	if your C compiler supports function prototypes	makefile.unix:	if not.(You have function prototypes if ckconfig.c put "#define HAVE_PROTOTYPES"in jconfig.h.)  You may want to start from one of the other makefiles ifthere is one for a system similar to yours. Look over the selected Makefile and adjust options as needed.  In particularyou may want to change the CC and CFLAGS definitions.  For instance, if youare using GCC, set CC=gcc.  If you had to use any compiler switches to getckconfig.c to work, make sure the same switches are in CFLAGS. If you are on a system that doesn't use makefiles, you'll need to set upproject files (or whatever you do use) to compile all the source files andlink them into executable files cjpeg, djpeg, jpegtran, rdjpgcom, and wrjpgcom.See the file lists in any of the makefiles to find out which files go intoeach program.  Note that the provided makefiles all make a "library" filelibjpeg first, but you don't have to do that if you don't want to; the filelists identify which source files are actually needed for compression,decompression, or both.  As a last resort, you can make a batch script thatjust compiles everything and links it all together; makefile.vms is an exampleof this (it's for VMS systems that have no make-like utility). Here are comments about some specific configuration decisions you'llneed to make: Command line style------------------ These programs can use a Unix-like command line style which supportsredirection and piping, like this:	cjpeg inputfile >outputfile	cjpeg <inputfile >outputfile	source program | cjpeg >outputfileThe simpler "two file" command line style is just	cjpeg inputfile outputfileYou may prefer the two-file style, particularly if you don't have pipes. You MUST use two-file style on any system that doesn't cope well with binarydata fed through stdin/stdout; this is true for some MS-DOS compilers, forexample.  If you're not on a Unix system, it's safest to assume you needtwo-file style.  (But if your compiler provides either the Posix-standardfdopen() library routine or a Microsoft-compatible setmode() routine, youcan safely use the Unix command line style, by defining USE_FDOPEN orUSE_SETMODE respectively.) To use the two-file style, make jconfig.h say "#define TWO_FILE_COMMANDLINE". Selecting a memory manager-------------------------- The IJG code is capable of working on images that are too big to fit in mainmemory; data is swapped out to temporary files as necessary.  However, thecode to do this is rather system-dependent.  We provide five differentmemory managers: * jmemansi.c	This version uses the ANSI-standard library routine tmpfile(),		which not all non-ANSI systems have.  On some systems		tmpfile() may put the temporary file in a non-optimal		location; if you don't like what it does, use jmemname.c. * jmemname.c	This version creates named temporary files.  For anything		except a Unix machine, you'll need to configure the		select_file_name() routine appropriately; see the comments		near the head of jmemname.c.  If you use this version, define		NEED_SIGNAL_CATCHER in jconfig.h to make sure the temp files		are removed if the program is aborted. * jmemnobs.c	(That stands for No Backing Store :-).)  This will compile on		almost any system, but it assumes you have enough main memory		or virtual memory to hold the biggest images you work with. * jmemdos.c	This should be used with most 16-bit MS-DOS compilers.		See the system-specific notes about MS-DOS for more info.		IMPORTANT: if you use this, define USE_MSDOS_MEMMGR in		jconfig.h, and include the assembly file jmemdosa.asm in the		programs.  The supplied makefiles and jconfig files for		16-bit MS-DOS compilers already do both. * jmemmac.c	Custom version for Apple Macintosh; see the system-specific		notes for Macintosh for more info. To use a particular memory manager, change the SYSDEPMEM variable in yourmakefile to equal the corresponding object file name (for example, jmemansi.oor jmemansi.obj for jmemansi.c). If you have plenty of (real or virtual) main memory, just use jmemnobs.c."Plenty" means about ten bytes for every pixel in the largest imagesyou plan to process, so a lot of systems don't meet this criterion.If yours doesn't, try jmemansi.c first.  If that doesn't compile, you'll haveto use jmemname.c; be sure to adjust select_file_name() for local conditions.You may also need to change unlink() to remove() in close_backing_store(). Except with jmemnobs.c or jmemmac.c, you need to adjust the DEFAULT_MAX_MEMsetting to a reasonable value for your system (either by adding a #define forDEFAULT_MAX_MEM to jconfig.h, or by adding a -D switch to the Makefile).This value limits the amount of data space the program will attempt toallocate.  Code and static data space isn't counted, so the actual memoryneeds for cjpeg or djpeg are typically 100 to 150Kb more than the max-memorysetting.  Larger max-memory settings reduce the amount of I/O needed toprocess a large image, but too large a value can result in "insufficientmemory" failures.  On most Unix machines (and other systems with virtualmemory), just set DEFAULT_MAX_MEM to several million and forget it.  At theother end of the spectrum, for MS-DOS machines you probably can't go muchabove 300K to 400K.  (On MS-DOS the value refers to conventional memory only.Extended/expanded memory is handled separately by jmemdos.c.)  BUILDING THE SOFTWARE===================== Now you should be able to compile the software.  Just say "make" (orwhatever's necessary to start the compilation).  Have a cup of coffee. Here are some things that could go wrong: If your compiler complains about undefined structures, you should be able toshut it up by putting "#define INCOMPLETE_TYPES_BROKEN" in jconfig.h. If you have trouble with missing system include files or inclusion of thewrong ones, read jinclude.h.  This shouldn't happen if you used configureor ckconfig.c to set up jconfig.h. There are a fair number of routines that do not use all of their parameters;some compilers will issue warnings about this, which you can ignore.  Thereare also a few configuration checks that may give "unreachable code" warnings.Any other warning deserves investigation. If you don't have a getenv() library routine, define NO_GETENV. Also see the system-specific hints, below.  TESTING THE SOFTWARE==================== As a quick test of functionality we've included a small sample image inseveral forms:	testorig.jpg	Starting point for the djpeg tests.	testimg.ppm	The output of djpeg testorig.jpg	testimg.bmp	The output of djpeg -bmp -colors 256 testorig.jpg	testimg.jpg	The output of cjpeg testimg.ppm	testprog.jpg	Progressive-mode equivalent of testorig.jpg.	testimgp.jpg	The output of cjpeg -progressive -optimize testimg.ppm(The first- and second-generation .jpg files aren't identical since JPEG islossy.)  If you can generate duplicates of the testimg* files then youprobably have working programs. With most of the makefiles, "make test" will perform the necessarycomparisons. If you're using a makefile that doesn't provide the test option, run djpegand cjpeg by hand and compare the output files to testimg* with whateverbinary file comparison tool you have.  The files should be bit-for-bitidentical. If the programs complain "MAX_ALLOC_CHUNK is wrong, please fix", then youneed to reduce MAX_ALLOC_CHUNK to a value that fits in type size_t.Try adding "#define MAX_ALLOC_CHUNK 65520L" to jconfig.h.  A less likelyconfiguration error is "ALIGN_TYPE is wrong, please fix": defining ALIGN_TYPEas long should take care of that one. If the cjpeg test run fails with "Missing Huffman code table entry", it's agood bet that you needed to define RIGHT_SHIFT_IS_UNSIGNED.  Go back to theconfiguration step and run ckconfig.c.  (This is a good plan for any othertest failure, too.) If you are using Unix (one-file) command line style on a non-Unix system,it's a good idea to check that binary I/O through stdin/stdout actuallyworks.  You should get the same results from "djpeg <testorig.jpg >out.ppm"as from "djpeg -outfile out.ppm testorig.jpg".  Note that the makefiles alluse the latter style and therefore do not exercise stdin/stdout!  If thischeck fails, try recompiling with USE_SETMODE or USE_FDOPEN defined.If it still doesn't work, better use two-file style. If you chose a memory manager other than jmemnobs.c, you should test thattemporary-file usage works.  Try "djpeg -bmp -colors 256 -max 0 testorig.jpg"and make sure its output matches testimg.bmp.  If you have any really largeimages handy, try compressing them with -optimize and/or decompressing with-colors 256 to make sure your DEFAULT_MAX_MEM setting is not too large. NOTE: this is far from an exhaustive test of the JPEG software; some modules,such as 1-pass color quantization, are not exercised at all.  It's just aquick test to give you some confidence that you haven't missed somethingmajor.  INSTALLING THE SOFTWARE======================= Once you're done with the above steps, you can install the software bycopying the executable files (cjpeg, djpeg, jpegtran, rdjpgcom, and wrjpgcom)to wherever you normally install programs.  On Unix systems, you'll also wantto put the man pages (cjpeg.1, djpeg.1, jpegtran.1, rdjpgcom.1, wrjpgcom.1)in the man-page directory.  The pre-fab makefiles don't support this stepsince there's such a wide variety of installation procedures on differentsystems. If you generated a Makefile with the "configure" script, you can just say	make installto install the programs and their man pages into the standard places.(You'll probably need to be root to do this.)  We recommend first saying	make -n installto see where configure thought the files should go.  You may need to editthe Makefile, particularly if your system's conventions for man pagefilenames don't match what configure expects. If you want to install the IJG library itself, for use in compiling otherprograms besides ours, then you need to put the four include files	jpeglib.h jerror.h jconfig.h jmorecfg.hinto your include-file directory, and put the library file libjpeg.a(extension may vary depending on system) wherever library files go.If you generated a Makefile with "configure", it will do what it thinksis the right thing if you say	make install-lib  OPTIONAL STUFF============== Progress monitor: If you like, you can #define PROGRESS_REPORT (in jconfig.h) to enable displayof percent-done progress reports.  The routine provided in cdjpeg.c merelyprints percentages to stderr, but you can customize it to do somethingfancier. Utah RLE file format support: We distribute the software with support for RLE image files (Utah RasterToolkit format) disabled, because the RLE support won't compile without theUtah library.  If you have URT version 3.1 or later, you can enable RLEsupport as follows:	1.  #define RLE_SUPPORTED in jconfig.h.	2.  Add a -I option to CFLAGS in the Makefile for the directory	    containing the URT .h files (typically the "include"	    subdirectory of the URT distribution).	3.  Add -L... -lrle to LDLIBS in the Makefile, where ... specifies	    the directory containing the URT "librle.a" file (typically the	    "lib" subdirectory of the URT distribution). Support for 12-bit-deep pixel data: The JPEG standard allows either 8-bit or 12-bit data precision.  (For color,this means 8 or 12 bits per channel, of course.)  If you need to work withdeeper than 8-bit data, you can compile the IJG code for 12-bit operation.To do so:  1. In jmorecfg.h, define BITS_IN_JSAMPLE as 12 rather than 8.  2. In jconfig.h, undefine BMP_SUPPORTED, RLE_SUPPORTED, and TARGA_SUPPORTED,     because the code for those formats doesn't handle 12-bit data and won't     even compile.  (The PPM code does work, as explained below.  The GIF     code works too; it scales 8-bit GIF data to and from 12-bit depth     automatically.)  3. Compile.  Don't expect "make test" to pass, since the supplied test     files are for 8-bit data. Currently, 12-bit support does not work on 16-bit-int machines. Note that a 12-bit version will not read 8-bit JPEG files, nor vice versa;so you'll want to keep around a regular 8-bit compilation as well.(Run-time selection of data depth, to allow a single copy that does both,is possible but would probably slow things down considerably; it's very lowon our to-do list.) The PPM reader (rdppm.c) can read 12-bit data from either text-format orbinary-format PPM and PGM files.  Binary-format PPM/PGM files which have amaxval greater than 255 are assumed to use 2 bytes per sample, LSB first(little-endian order).  As of early 1995, 2-byte binary format is notofficially supported by the PBMPLUS library, but it is expected that afuture release of PBMPLUS will support it.  Note that the PPM reader willread files of any maxval regardless of the BITS_IN_JSAMPLE setting; incomingdata is automatically rescaled to either maxval=255 or maxval=4095 asappropriate for the cjpeg bit depth. The PPM writer (wrppm.c) will normally write 2-byte binary PPM or PGMformat, maxval 4095, when compiled with BITS_IN_JSAMPLE=12.  Since thisformat is not yet widely supported, you can disable it by compiling wrppm.cwith PPM_NORAWWORD defined; then the data is scaled down to 8 bits to make astandard 1-byte/sample PPM or PGM file.  (Yes, this means still another copyof djpeg to keep around.  But hopefully you won't need it for very long.Poskanzer's supposed to get that new PBMPLUS release out Real Soon Now.) Of course, if you are working with 12-bit data, you probably have it storedin some other, nonstandard format.  In that case you'll probably want towrite your own I/O modules to read and write your format. Note that a 12-bit version of cjpeg always runs in "-optimize" mode, inorder to generate valid Huffman tables.  This is necessary because ourdefault Huffman tables only cover 8-bit data. Removing code: If you need to make a smaller version of the JPEG software, some optionalfunctions can be removed at compile time.  See the xxx_SUPPORTED #defines injconfig.h and jmorecfg.h.  If at all possible, we recommend that you leave indecoder support for all valid JPEG files, to ensure that you can read anyone'soutput.  Taking out support for image file formats that you don't use is themost painless way to make the programs smaller.  Another possibility is toremove some of the DCT methods: in particular, the "IFAST" method may not beenough faster than the others to be worth keeping on your machine.  (If youdo remove ISLOW or IFAST, be sure to redefine JDCT_DEFAULT or JDCT_FASTESTto a supported method, by adding a #define in jconfig.h.)  OPTIMIZATION============ Unless you own a Cray, you'll probably be interested in making the JPEGsoftware go as fast as possible.  This section covers some machine-dependentoptimizations you may want to try.  We suggest that before trying any ofthis, you first get the basic installation to pass the self-test step.Repeat the self-test after any optimization to make sure that you haven'tbroken anything. The integer DCT routines perform a lot of multiplications.  Thesemultiplications must yield 32-bit results, but none of their input valuesare more than 16 bits wide.  On many machines, notably the 680x0 and 80x86

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