文件列表:

SOURCE (0, 1996-09-02)
SOURCE\CDERROR.PAS (8725, 1996-07-31)
SOURCE\CDJPEG.PAS (9497, 1996-08-26)
SOURCE\CJPEG.PAS (24721, 1996-08-28)
SOURCE\DEMO.PAS (645, 1996-08-10)
SOURCE\DJPEG.PAS (23374, 1996-08-20)
SOURCE\EXAMPLE.PAS (18935, 1996-08-15)
SOURCE\JCAPIMIN.PAS (11355, 1996-08-22)
SOURCE\JCAPISTD.PAS (8514, 1996-08-22)
SOURCE\JCCOEFCT.PAS (18538, 1996-08-20)
SOURCE\JCCOLOR.PAS (17930, 1996-08-22)
SOURCE\JCDCTMGR.PAS (16101, 1996-08-28)
SOURCE\JCHUFF.PAS (31226, 1996-09-01)
SOURCE\JCINIT.PAS (2814, 1996-08-20)
SOURCE\JCMAINCT.PAS (10919, 1996-08-20)
SOURCE\JCMARKER.PAS (18260, 1996-08-20)
SOURCE\JCMASTER.PAS (22655, 1996-08-28)
SOURCE\JCOMAPI.PAS (3376, 1996-08-22)
SOURCE\JCONFIG.INC (3360, 1996-09-01)
SOURCE\JCPARAM.PAS (23087, 1996-08-28)
SOURCE\JCPHUFF.PAS (29414, 1996-09-01)
SOURCE\JCPREPCT.PAS (14138, 1996-08-20)
SOURCE\JCSAMPLE.PAS (22946, 1996-08-22)
SOURCE\JCTRANS.PAS (15762, 1996-08-22)
SOURCE\JDAPIMIN.PAS (18083, 1996-08-22)
SOURCE\JDAPISTD.PAS (12544, 1996-08-20)
SOURCE\JDATADST.PAS (5807, 1996-08-22)
SOURCE\JDATASRC.PAS (8206, 1996-08-22)
SOURCE\JDCOEFCT.PAS (29495, 1996-08-28)
SOURCE\JDCOLOR.PAS (15689, 1996-08-22)
SOURCE\JDCT.PAS (3878, 1996-09-02)
SOURCE\JDDCTMGR.PAS (9792, 1996-08-22)
SOURCE\JDEFERR.PAS (19885, 1996-08-28)
SOURCE\JDHUFF.PAS (34977, 1996-08-22)
SOURCE\JDINPUT.PAS (14993, 1996-08-22)
SOURCE\JDMAINCT.PAS (23441, 1996-08-20)
SOURCE\JDMARKER.PAS (70657, 1996-08-22)
SOURCE\JDMASTER.PAS (22878, 1996-08-21)
SOURCE\JDMERGE.PAS (18578, 1996-08-20)
... ...

_____________________________________________________________________________ PASJPEG September 18th, 1996 Based on the Independent JPEG Group's free JPEG library rev 6a Copyright 1996 by NOMSSI NZALI Jacques H. C. [kn&n DES] See "Legal issues" for conditions of distribution and use. _____________________________________________________________________________ Information in this file ======================== o Introduction o Notes o File list o Translation o Legal issues o Archive Locations Introduction ============ PASJPEG is a port of the sixth public release of the IJG C source (release 6a of 7-Feb-96) [3], that implements JPEG baseline, extended-sequential, and progressive compression processes to Turbo Pascal 7.0 for DOS (TP). The code has been tested under Delphi 2.0 [6], it can be ported to other Pascal environments, since many compilers try to be compatible to TP. JPEG (pronounced "jay-peg") is a standardized familly of algorithms for compression of continous tone still images. Most JPEG processes are lossy, the output image is not exactly identical to the input image. However, on typical photographic images, very good compression levels can be obtained with no visible change, and remarkably high compression levels are possible if you can tolerate a low-quality image [1],[2]. The Independent JPEG Group (IJG) has created a free, portable C library for JPEG compression and decompression of JPEG images. The IJG documentation (system architecture, using the IJG JPEG library, usage and file list) is a must read. The files DEMO.PAS, TEST.PAS, CJPEG.PAS, DJPEG.PAS and EXAMPLE.PAS demonstrate the usage of the JPEG decompression and compression library. The RDJPGCOM application shows how to parse a JFIF file. Notes: ====== * Please report any errors/problems you may find in code and in the documentation (e.g. this README.TXT file). * The sample applications (CJPEG, DJPEG) doesn't support all the options of the original C code. JPEGTRANS and WRJPGCOM are not ported yet. * Environment variable JPEGMEM syntax changed; * You may want to create online help from the TP sources using the SCANHELP utility by Duncan J. Murdoch at SimTel and garbo. File list ========= A road map to the files in the PASJPEG distribution readme.txt Introduction, Documentation Configuration/installation files jconfig.inc Configuration declarations. jpeglib.pas JPEG library's exported data and function declarations. jmorecfg.pas Additional configuration declarations; need not be changed for a standard installation. jerror.pas Declares JPEG library's error and trace message codes. jinclude.pas jdct.pas Private declarations for forward & reverse DCT subsystems. These files contain most of the functions intended to be called directly by an application program: jcapimin.pas Application program interface: core routines for compression. jcapistd.pas Application program interface: standard compression. jdapimin.pas Application program interface: core routines for decompression. jdapistd.pas Application program interface: standard decompression. jcomapi.pas Application program interface routines common to compression and decompression. jcparam.pas Compression parameter setting helper routines. jctrans.pas API and library routines for transcoding compression. jdtrans.pas API and library routines for transcoding decompression. Compression side of the library: jcinit.pas Initialization: determines which other modules to use. jcmaster.pas Master control: setup and inter-pass sequencing logic. jcmainct.pas Main buffer controller (preprocessor => JPEG compressor). jcprepct.pas Preprocessor buffer controller. jccoefct.pas Buffer controller for DCT coefficient buffer. jccolor.pas Color space conversion. jcsample.pas Downsampling. jcdctmgr.pas DCT manager (DCT implementation selection & control). jfdctint.pas Forward DCT using slow-but-accurate integer method. jfdctfst.pas Forward DCT using faster, less accurate integer method. jfdctflt.pas Forward DCT using floating-point arithmetic. jchuff.pas Huffman entropy coding for sequential JPEG. jcphuff.pas Huffman entropy coding for progressive JPEG. jcmarker.pas JPEG marker writing. jdatadst.pas Data destination manager for stdio output. Decompression side of the library: jdmaster.pas Master control: determines which other modules to use. jdinput.pas Input controller: controls input processing modules. jdmainct.pas Main buffer controller (JPEG decompressor => postprocessor). jdcoefct.pas Buffer controller for DCT coefficient buffer. jdpostct.pas Postprocessor buffer controller. jdmarker.pas JPEG marker reading. jdhuff.pas Huffman entropy decoding for sequential JPEG. jdphuff.pas Huffman entropy decoding for progressive JPEG. jddctmgr.pas IDCT manager (IDCT implementation selection & control). jidctint.pas Inverse DCT using slow-but-accurate integer method. jidctfst.pas Inverse DCT using faster, less accurate integer method. jidctflt.pas Inverse DCT using floating-point arithmetic. jidctred.pas Inverse DCTs with reduced-size outputs. jidct2d.pas Direct 2D Inverse DCT - NOT READY YET jdsample.pas Upsampling. jdcolor.pas Color space conversion. jdmerge.pas Merged upsampling/color conversion (faster, lower quality). jquant1.pas One-pass color quantization using a fixed-spacing colormap. jquant2.pas Two-pass color quantization using a custom-generated colormap. Also handles one-pass quantization to an externally given map. jdatasrc.pas Data source manager for stdio input. Support files for both compression and decompression: jerror.pas Standard error handling routines (application replaceable). jmemmgr.pas System-independent (more or less) memory management code. jutils.pas Miscellaneous utility routines. jmemmgr.pas relies on a system-dependent memory management module. The PASJPEG distribution includes the following implementations of the system- dependent module: jmemnobs.pas "No backing store": assumes adequate virtual memory exists. jmemdos.pas Custom implementation for MS-DOS: knows about extended and expanded memory as well as temporary files. jmemsys.pas A skeleton with all the declaration you need to create a working system-dependent JPEG memory manager. Exactly one of the system-dependent modules should be configured into an installed JPEG library (see install.doc for hints about which one to use). On unusual systems you may find it worthwhile to make a special system-dependent memory manager. jmemdosa.pas BASM 80x86 assembly code support for jmemdos.pas; used only in MS-DOS-specific configurations of the JPEG library. Additional Applications demo.pas Demo program, uses example.pas example.pas Sample code for calling JPEG library. test.pas Sample skeleton code for example.pas cdjpeg.pas Declarations shared by cjpeg/djpeg modules. cderror.pas Additional error and trace message codes for cjpeg/djpeg. Not used, Those errors have been added to jdeferr. cjpeg.pas Main program for cjpeg. djpeg.pas Main program for djpeg. jpegtran.pas Main program for jpegtran.- NOT READY YET cdjpeg.pas Utility routines used by all three programs. rdcolmap.pas Code to read a colormap file for djpeg's "-map" switch. rdswitch.pas Code to process some of cjpeg's more complex switches. Also used by jpegtran. - NOT READY YET Image file writer modules for djpeg: wrbmp.pas BMP file output. wrtarga.pas Targa file output. Image file reader modules for cjpeg: rdbmp.pas BMP file input. rdtarga.pas Targa file input. - NOT READY YET This program does not depend on the JPEG library. rdjpgcom.pas Stand-alone rdjpgcom application. Translation =========== TP is unit-centric, exported type definitions and routines are declared in the "interface" part of the unit, "make" files are not needed. Macros are not supported, they were either copied as needed or translated to Pascal routines (procedure). The procedures will be replaced by code in later releases. Conditional defines that indicate whether to include various optional functions are defined in the file JCONFIG.INC. This file is included first in all source files. The base type definitions are in the unit JMORECFG.PAS. The error handling macros have been converted to procedures in JERROR.PAS. The error codes are in JDEFERR.PAS. jpegint.h and jpeglib.h were merged into one large unit JPEGLIB.PAS containing type definitions with global scope. The translation of the header file is the most sophisticated work, a good understanding of the syntax is required. Once the header files are done, the translation turns into a lot of editing work. Each C source file was converted to a unit by editing the syntax (separate variable definition and usage, define labels, group variable definitions, expanding macros, etc). The IJG source labels routines GLOBAL, METHODDEF and LOCAL. All globals routines are in the interface section of the units. The "far" directive is used for methods (METHODDEF). Some C -> Pascal examples. * "{" -> "begin" "->" -> "^." " = " -> " := " "<<" -> " shl " "}" -> "end;" "!=" -> "<>" " == " -> " = " ">>" -> " shr " "/*" -> "{" routine -> function "0x" -> "$" "*/" -> "}" (void) procedure "NULL" -> "NIL" * structs are records, Unions are variable records, pointers are always far, the operators && and || (and/or) have not the same priority in both languages, so parenthesis are important. The Pascal "case" doesn't have the falltrough option of the C "switch" statement, my work around is to split one "switch" statement into many case statements. * The pointer type in C is not readily interchangeable. It is used to address an array (Pascal pointer to an array) or in pointer arithmetic a pointer to a single element. I've used the Inc() statement with type casting to translate pointer arithmetic most of the time. C example: typedef JSAMPLE* JSAMPROW; /* ptr to one image row of pixel samples. */ Pascal type JSAMPLE_PTR = ^JSAMPLE; { ptr to a single pixel sample. } jTSample = 0..(MaxInt div SIZEOF(JSAMPLE))-1; JSAMPLE_ARRAY = Array[jTSample] of JSAMPLE; {far} JSAMPROW = ^JSAMPLE_ARRAY; { ptr to one image row of pixel samples. } The following code JSAMPROW buffer0, buffer1; /* ptr to a JSAMPLE buffer. */ ... buffer1 = buffer0 + i; can be translated to var buffer0, buffer1 : JSAMPROW; ... buffer1 := buffer0; Inc(JSAMPLE_PTR(buffer1), i); or buffer1 := JSAMPROW(@ buffer0^[i]); Declaring the variables as JSAMPLE_PTR may reduce type casting in some places. I use help pointers to handle negative array offsets. While translating the type of function parameter from C to Pascal, one can often use "var", "const", or "array of" parameters instead of pointers. While translating for(;;)-loops with more than one induction variable to Pascal "for to/downto do"-loops, the extra induction variables have to be manually updated at the end of the loop and before "continue"-statements. Legal issues ============ Copyright (C) 1996 by Jacques Nomssi Nzali This software is provided 'as-is', without any express or implied warranty. In no event will the author be held liable for any damages arising from the use of this software. Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions: 1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required. 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. 3. This notice may not be removed or altered from any source distribution. Archive Locations: ================== [1] Thomas G. Lane, JPEG FAQ in comp.graphics.misc and related newsgroups [2] Wallace, Gregory K.: The JPEG Still Picture Compression Standard ftp.uu.net, graphics/jpeg/wallace.ps.Z [3] The Independent JPEG Group C library for JPEG encoding and decoding, rev 6a. ftp://ftp.uu.net/graphics/jpeg/ or SimTel in msdos/graphics/ [4] JPEG implementation, written by the PVRG group at Stanford, ftp havefun.stanford.edu:/pub/jpeg/JPEGv1.2.tar.Z. [5] PASJPEG.ZIP at NView ftp site ftp://druckfix.physik.tu-chemnitz.de/pub/nv/ http://www.tu-chemnitz.de/~nomssi/pub/pasjpeg.zip [6] Delphi 2.0 Image Viewer Application using PASJPEG, by Detlef Meister, http://w3.rz.fthw-berlin.de/~meister/index.html _____________________________________________________________________________

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