Pioneer BDP-320 - Manual (Page 50)

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It a ppears that the arithmetic coding option of the JPEG
s pec is covered by patents owned by IBM, AT&T, and
Mitsubishi. Hence a rithmetic coding cannot legally be
used without obtaining one o r more licenses. For this
reason, support for arithmetic coding has been removed
f
rom the free JPEG software. (Since arithmetic coding
provides only a marginal gain over the unpatented Huffman
mode, it is unlikely that ve
ry many implementations will
su pport it.) So far as we are aware, there are no patent
restrictions on the remaining code.
The IJG dist
ribution formerly included code to read and
w rite GIF files. To avoid entanglement with the Unisys LZW
patent, GIF reading support has been removed altogether,
and the GIF w
riter has been simplified to produce
uncom pressed GIFs. This technique does not use the LZW
algo rithm; the resulting GIF files are larger than usual, but
a re readable by all standard GIF decoders.
We a re required to state that
“The G raphics Interchange Format(c) is the Copyright
property of CompuServe Incorporated. GIF(sm) is a
Se
rvice Mark property of CompuServe Incorporated.”
REFERENCES
We highly
recommend reading one or more of these
references before trying to understand the innards of the
JPEG softwa
re.
The best sho rt technical introduction to the JPEG
com pression algorithm is
Wallace, G regory K. “The JPEG Still Picture Compression
Standa rd”,
Communications of the ACM, A pril 1991 (vol. 34 no. 4),
pp. 30-44.
(Adjacent a rticles in that issue discuss MPEG motion
picture compression, applications of JPEG, and related
to
pics.) If you don’t have the CACM issue handy, a
PostSc ript file containing a revised version of Wallace’s
a rticle is available at ftp://ftp.uu.net/graphics/jpeg/
wallace. ps.gz. The file (actually a preprint for an article that
a ppeared in IEEE Trans. Consumer Electronics) omits the
sam ple images that appeared in CACM, but it includes
co rrections and some added material. Note: the Wallace
a rticle is copyright ACM and IEEE, and it may not be used
fo r commercial purposes.
A somewhat less technical, mo re leisurely introduction to
JPEG can be found in The Data Com pression Book by Mark
Nelson and Jean-lou p Gailly, published by M&T Books (New
Yo rk), 2nd ed. 1996, ISBN 1-55851-434-1. This book provides
good ex planations and example C code for a multitude of
com pression methods including JPEG. It is an excellent
sou rce if you are comfortable reading C code but don’t
know much about data com pression in general. The book’s
JPEG sam ple code is far from industrial-strength, but when
you a re ready to look at a full implementation, you’ve got
one he re...
The best full desc ription of JPEG is the textbook “JPEG Still
Image Data Com pression Standard” by William B.
Pennebake r and Joan L. Mitchell, published by Van
Nost rand Reinhold, 1993, ISBN 0-442-01272-1. Price
US$59.95, 638 pp. The book includes the complete text of
the ISO JPEG standa rds (DIS 10918-1 and draft DIS 10918-
2). This is by fa r the most complete exposition of JPEG in
existence, and we highly recommend it.
The JPEG standa rd itself is not available electronically; you
must o rder a paper copy through ISO or ITU. (Unless you
feel a need to own a ce rtified official copy, we recommend
buying the Pennebake r and Mitchell book instead; it’s
much chea per and includes a great deal of useful
ex planatory material.) In the USA, copies of the standard
may be o rdered from ANSI Sales at (212) 642-4900, or from
Global Enginee ring Documents at (800) 854-7179. (ANSI
doesn’t take c redit card orders, but Global does.) It’s not
chea p: as of 1992, ANSI was charging $95 for Part 1 and $47
fo r Part 2, plus 7% shipping/handling. The standard is
divided into two parts, Part 1 being the actual specification,
while Pa rt 2 covers compliance testing methods. Part 1 is
titled “Digital Com pression and Coding of Continuous-tone
Still Images, Pa rt 1: Requirements and guidelines” and has
document numbe rs ISO/IEC IS 10918-1, ITU-T T.81. Part 2 is
titled “Digital Com pression and Coding of Continuous-tone
Still Images, Pa rt 2: Compliance testing” and has
document numbe rs ISO/IEC IS 10918-2, ITU-T T.83.
Some extensions to the o riginal JPEG standard are defined
in JPEG Pa rt 3, a newer ISO standard numbered ISO/IEC IS
10918-3 and ITU-T T.84. IJG cu rrently does not support any
Pa rt 3 extensions.
The JPEG standa rd does not specify all details of an
inte rchangeable file format. For the omitted details we
follow the “JFIF” conventions, revision 1.02. A copy of the
JFIF s pec is available from:
Lite rature Department
C-Cube Mic rosystems, Inc.
1778 McCa rthy Blvd.
Mil pitas, CA 95035
phone (408) 944-6300, fax (408) 944-6314
A PostSc ript version of this document is available by FTP at
ft p://ftp.uu.net/graphics/jpeg/jfif.ps.gz. There is also a plain
text ve rsion at ftp://ftp.uu.net/graphics/jpeg/jfif.txt.gz, but it
is missing the figu res.
The TIFF 6.0 file fo rmat specification can be obtained by FTP
f rom ftp://ftp.sgi.com/graphics/tiff/TIFF6.ps.gz. The JPEG
inco rporation scheme found in the TIFF 6.0 spec of 3-June-
92 has a numbe r of serious problems. IJG does not
recommend use of the TIFF 6.0 design (TIFF Compression
tag 6). Instead, we
recommend the JPEG design proposed
by TIFF Technical Note #2 (Com pression tag 7). Copies of
this Note can be obtained f rom ftp.sgi.com or from ftp://
ft p.uu.net/graphics/jpeg/. It is expected that the next
revision of the TIFF spec will replace the 6.0 JPEG design
with the Note’s design. Although IJG’s own code does not
su
pport TIFF/JPEG, the free libtiff library uses our library to
im plement TIFF/JPEG per the Note. libtiff is available from
ft p://ftp.sgi.com/graphics/tiff/.
ARCHIVE LOCATIONS
The “official” a
rchive site for this software is ftp.uu.net
(Inte rnet address 192.48.96.9). The most recent released
ve rsion can always be found there in directory graphics/
j peg. This particular version will be archived as ftp://
ft p.uu.net/graphics/jpeg/jpegsrc.v6b.tar.gz. If you don’t
have di rect Internet access, UUNET’s archives are also
available via UUCP; contact hel [email protected] for
info rmation on retrieving files that way.
Nume rous Internet sites maintain copies of the UUNET
files. Howeve r, only ftp.uu.net is guaranteed to have the
latest official ve rsion.
You can also obtain this softwa re in DOS-compatible “zip”
a rchive format from the SimTel archives (ftp://
ft p.simtel.net/pub/simtelnet/msdos/graphics/), or on
Com puServe in the Graphics Support forum (GO
CIS:GRAPHSUP), lib rary 12 JPEG Tools. Again, these
ve rsions may sometimes lag behind the ftp.uu.net release.
The JPEG FAQ (F requently Asked Questions) article is a
useful sou rce of general information about JPEG. It is
u pdated constantly and therefore is not included in this
dist ribution. The FAQ is posted every two weeks to Usenet
newsg roups comp.graphics.misc, news.answers, and
othe r groups. It is available on the World Wide Web at http:/
/www.faqs.o rg/faqs/jpeg-faq/ and other news.answers
a rchive sites, including the official news.answers archive at
rtfm.mit.edu: ftp://rtfm.mit.edu/pub/usenet/news.answers/
j
peg-faq/. If you don’t have Web or FTP access, send e-mail
to mail-se [email protected] with body
send usenet/news.answe rs/jpeg-faq/part1
send usenet/news.answe rs/jpeg-faq/part2
RELATED SOFTWARE
Nume
rous viewing and image manipulation programs now
su pport JPEG. (Quite a few of them use this library to do so.)
The JPEG FAQ desc ribed above lists some of the more
popular free and shareware viewers, and tells where to
obtain them on Inte
rnet.
If you a re on a Unix machine, we highly recommend Jef
Poskanze r’s free PBMPLUS software, which provides many
useful o perations on PPM-format image files. In particular,
it can conve rt PPM images to and from a wide range of
othe r formats, thus making cjpeg/djpeg considerably more
useful. The latest ve rsion is distributed by the NetPBM
g roup, and is available from numerous sites, notably ftp://
wua rchive.wustl.edu/graphics/graphics/packages/
NetPBM/. Unfo rtunately PBMPLUS/NETPBM is not nearly
as portable as the IJG software is; you are likely to have
difficulty making it wo rk on any non-Unix machine.
A diffe rent free JPEG implementation, written by the PVRG
g roup at Stanford, is available from ftp://
havefun.stanford.edu/pub/jpeg/. This program is designed
fo
r research and experimentation rather than production
use; it is slowe r, harder to use, and less portable than the
IJG code, but it is easie r to read and modify. Also, the PVRG
code su pports lossless JPEG, which we do not. (On the
othe r hand, it doesn’t do progressive JPEG.)
FILE FORMAT WARS
Some JPEG
programs produce files that are not compatible
with ou r library. The root of the problem is that the ISO
JPEG committee failed to s pecify a concrete file format.
Some vendo rs “filled in the blanks” on their own, creating
proprietary formats that no one else could read. (For
exam
ple, none of the early commercial JPEG
im plementations for the Macintosh were able to exchange
com pressed files.)
The file fo rmat we have adopted is called JFIF (see
REFERENCES). This fo rmat has been agreed to by a
numbe r of major commercial JPEG vendors, and it has
become the de facto standa rd. JFIF is a minimal or “low
end” representation. We recommend the use of TIFF/JPEG
(TIFF revision 6.0 as modified by TIFF Technical Note #2) for
“high end” a pplications that need to record a lot of
additional data about an image. TIFF/JPEG is fai rly new and
not yet widely su pported, unfortunately.
The u pcoming JPEG Part 3 standard defines a file format
called SPIFF. SPIFF is inte roperable with JFIF, in the sense
that most JFIF decode rs should be able to read the most
common va riant of SPIFF. SPIFF has some technical
advantages ove r JFIF, but its major claim to fame is simply
that it is an official standa rd rather than an informal one. At
this point it is unclear whether SPIFF will supersede JFIF or
whethe r JFIF will remain the de-facto standard. IJG intends
to su pport SPIFF once the standard is frozen, but we have
not decided whethe r it should become our default output
fo rmat or not. (In any case, our decoder will remain capable
of reading JFIF indefinitely.)
Va rious proprietary file formats incorporating JPEG
com pression also exist. We have little or no sympathy for
the existence of these fo rmats. Indeed, one of the original
reasons for developing this free software was to help force
conve
rgence on common, open format standards for JPEG
files. Don’t use a proprietary file format!
TO DO
The majo
r thrust for v7 will probably be improvement of
visual quality. The cu rrent method for scaling the
quantization tables is known not to be ve ry good at low Q
values. We also intend to investigate block bounda ry
smoothing, “ poor man’s variable quantization”, and other
means of im proving quality-vs-file-size performance
without sac rificing compatibility.
In futu re versions, we are considering supporting some of
the u pcoming JPEG Part 3 extensions --- principally,
va riable quantization and the SPIFF file format.
As always, speeding things up is of great interest.
Please send bug
reports, offers of help, etc. to jpeg-
[email protected].
libupnp
Co pyright (c) 2000-2003 Intel Corporation
All rights reserved.
Redist ribution and use in source and binary forms, with or
without modification, a re permitted provided that the
following conditions a re met:
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT
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AVC/H.264
THIS PRODUCT IS LICENSED UNDER THE AVC PATENT
PORTFOLIO LICENSE FOR THE PERSONAL AND NON-
COMMERCIAL USE OF A CONSUMER TO (i) ENCODE
VIDEO IN COMPLIANCE WITH THE AVC STANDARD (”AVC
VIDEO”) AND/OR (ii) DECODE AVC VIDEO THAT WAS
ENCODED BY A CONSUMER ENGAGED IN A PERSONAL
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SHALL BE IMPLIED FOR ANY OTHER USE. ADDITIONAL
INFORMATION MAY BE OBTAINED FROM MPEG LA, L.L.C.
SEE HTTP://MPEGLA.COM.
GNU GENERAL PUBLIC LICENSE
Ve rsion 2, June 1991
Co pyright © 1989, 1991 Free Software Foundation, Inc., 51
F ranklin Street, Fifth Floor, Boston, MA 02110-1301 USA
Eve ryone is permitted to copy and distribute verbatim
co pies of this license document, but changing it is not
allowed.
Preamble
The licenses fo
r most software are designed to take away
you r freedom to share and change it. By contrast, the GNU
Gene ral Public License is intended to guarantee your
f reedom to share and change free software - to make sure
the softwa re is free for all its users. This General Public
License a pplies to most of the Free Software Foundation’s
softwa re and to any other program whose authors commit
to using it. (Some othe r Free Software Foundation software
is cove red by the GNU Lesser General Public License
instead.) You can a pply it to your programs, too.
When we s peak of free software, we are referring to
f reedom, not price. Our General Public Licenses are
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