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Archive-name: auto/comp.compression/Version-4-of-free-JPEG-software-released

The Independent JPEG Group is proud to announce the fourth public release
of our free JPEG image compression software.

The C source code, documentation, and test files are available for anonymous
FTP from FTP.UU.NET (137.39.1.9), file graphics/jpeg/jpegsrc.v4.tar.Z.
The package will shortly be available on CompuServe, in the GRAPHSUPPORT
forum (GO PICS), library 15, as jpsrc4.zip.  We intend to post the source
code in comp.sources.misc and executables in appropriate binaries groups.


The distributed code provides conversion between JPEG "JFIF" format and
image files in PBMPLUS PPM/PGM, Utah RLE, Truevision Targa, and GIF file
formats.  The core compression and decompression modules can easily be
reused in other programs, such as image viewers.  The package is highly
portable C code; we have tested it on many machines ranging from PCs to
Crays.

Important improvements over version 3 include:

* Significant speedups.  The basic JPEG compression and decompression
  operations are typically about a factor of 2 faster than v3.  (Your
  mileage will vary depending on CPU type and C compiler.)

* Improved image quality, due to more accurate DCT and resampling
  algorithms.

* Error recovery capability has been added to the decompressor, so that
  it can cope with damaged JPEG files.  While damage to the compressed
  data will scramble the output image, the effects of damage can be
  confined to small areas of the image if the file was originally created
  with "restart" markers.  Even severe damage will only result in loss of
  the damaged restart segments; the rest of the image can still be recovered.

* Redesigned command line switches provide access to more JPEG parameter
  settings, including restart marker generation in the compressor.

* There is an option for smoothing the input image before JPEG compression.
  This helps a lot when converting dithered GIFs to JPEG.

* Portability is even better than v3.


We are releasing this software for both noncommercial and commercial use.
Companies are welcome to use it as the basis for JPEG-related products.
We do not ask a royalty, although we do ask for an acknowledgement in
product literature (see the README file in the distribution for details).
We hope to make this software industrial-quality --- although, as with
anything that's free, we offer no warranty and accept no liability.

Please direct any questions about this software to jpeg-info@uunet.uu.net.

-- 
			Dr. Thomas G. Lane
			organizer, Independent JPEG Group
Internet: tgl@cs.cmu.edu	BITNET: tgl%cs.cmu.edu@cmuccvma