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JPEG image compression FAQ, part 2/2
Section - [15] Freely available source code for JPEG

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Free, portable C code for JPEG compression is available from the Independent
JPEG Group.  Source code, documentation, and test files are included.
Version 6b is available from ftp.uu.net:/graphics/jpeg/jpegsrc.v6b.tar.gz.
If you are on a PC you may prefer ZIP archive format, which you can find at
ftp.simtel.net:/pub/simtelnet/msdos/graphics/jpegsr6b.zip (or at any
Simtel mirror site).  On CompuServe, see the Graphics Learning forum
(GO CIS:LEARN), library 12 "JPEG Tools", file jpegsr6b.zip.

The IJG code includes a reusable JPEG compression/decompression library,
plus sample applications "cjpeg" and "djpeg", which perform conversion
between JPEG JFIF format and image files in PPM/PGM (PBMPLUS), BMP,
Utah RLE, and Targa formats.  A third application "jpegtran" provides
lossless transcoding between different JPEG formats --- for example, it can
convert a baseline JPEG file to an equivalent progressive JPEG file.
jpegtran can also do lossless rotation and flipping of JPEG files.  Two
small applications "wrjpgcom" and "rdjpgcom" insert and extract textual
comments in JFIF files.  The package is highly portable; it has been used
successfully on many machines ranging from Apple IIs to Crays.

The IJG code is free for both noncommercial and commercial use; only an
acknowledgement in your documentation is required to use it in a product.
(See the README file in the distribution for details.)

The IJG code has recently been translated into Pascal --- see
ftp.simtel.net:/pub/simtelnet/msdos/turbopas/pasjpg10.zip.  This version
has been tested under Turbo Pascal and Delphi, and it should be portable
to compatible Pascal compilers.


A different free JPEG implementation, written by the PVRG group at Stanford,
is available from havefun.stanford.edu:/pub/jpeg/JPEGv1.2.1.tar.Z.  The PVRG
code is designed for research and experimentation rather than production
use; it is slower, harder to use, and less portable than the IJG code, but
the PVRG code is easier to understand.  Also, the PVRG code supports (the
original form of) lossless JPEG, while the IJG code does not.  But PVRG does
not support progressive JPEG.

There's also a lossless-JPEG-only implementation available from Cornell,
ftp.cs.cornell.edu:/pub/multimed/ljpg.tar.Z.  Caution: the Cornell coder
is known to have bugs for 16-bit data.

Neither the PVRG nor Cornell codecs are being actively maintained, but the
IJG code is.

User Contributions:

Report this comment as inappropriate
Nov 11, 2018 @ 11:11 am
Artikel ini menjawab Pertanyaan yang Sering Diajukan tentang kompresi gambar JPEG.
Ini adalah bagian 1, yang meliputi pertanyaan umum dan jawaban tentang JPEG. Bagian 2
memberikan petunjuk khusus sistem dan rekomendasi program. Seperti biasa,
saran untuk peningkatan FAQ ini disambut baik.

Baru sejak versi 14 Maret 1999:
* Memperluas item 10 untuk mendiskusikan rotasi tanpa loss dan pemangkasan JPEG.


Artikel ini mencakup bagian-bagian berikut:

Pertanyaan dasar:

[1] Apa itu JPEG?
[2] Mengapa menggunakan JPEG?
[3] Kapan saya harus menggunakan JPEG, dan kapan saya harus tetap menggunakan GIF?
[4] Seberapa baik gambar kompresi JPEG?
[5] Pengaturan "kualitas" apa yang bagus untuk JPEG?
[6] Di mana saya bisa mendapatkan perangkat lunak JPEG?
[7] Bagaimana cara melihat gambar JPEG yang diposkan di Usenet?

Pertanyaan lanjutan lainnya:

[8] Apa itu kuantisasi warna?
[9] Apa beberapa aturan praktis untuk mengkonversi gambar GIF ke JPEG?
[10] Apakah kehilangan terakumulasi dengan kompresi / dekompresi berulang?
[11] Apa itu JPEG progresif?
[12] Dapatkah saya membuat JPEG transparan?
[13] Apakah tidak ada JPEG lossless?
[14] Mengapa semua argumen tentang format file?
[15] Bagaimana saya mengenali format file yang saya miliki, dan apa yang harus saya lakukan?
[16] Masalah kompatibilitas umum apa saja yang ada di sana?
[17] Bagaimana cara kerja JPEG?
[18] Bagaimana dengan pengkodean aritmatika?
[19] Mungkinkah FPU mempercepat JPEG? Bagaimana dengan chip DSP?
[20] Apakah tidak ada standar M-JPEG untuk film?
[21] Bagaimana jika saya membutuhkan lebih dari 8-bit presisi?
[22] Bagaimana program saya mengekstrak dimensi gambar dari file JPEG?

Miscellaneous:

[23] Di mana saya bisa belajar tentang menggunakan gambar di World Wide Web?
[24] Di mana daftar FAQ diarsipkan?


Artikel ini dan rekannya diposting setiap 2 minggu. Jika Anda tidak dapat menemukannya
Bagian 2, Anda bisa mendapatkannya dari arsip di rtfm.mit.edu
(lihat "[24] Di mana daftar FAQ diarsipkan?"). Bagian 2 sangat sering berubah;
dapatkan salinan baru jika yang Anda baca berusia lebih dari beberapa bulan.

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Top Document: JPEG image compression FAQ, part 2/2
Previous Document: [14] Other systems
Next Document: [16] Which programs support progressive JPEG?

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Last Update March 27 2014 @ 02:11 PM