Yamaha DSP-Z7 User Manual download pdf (Page 153)

The file format we have adopted is called JFIF (see REFERENCES). This format has

been agreed to by a number of major commercial JPEG vendors, and it has become the

de facto standard. 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” applications that need to record a lot of additional data about an image. TIFF/JPEG

is fairly new and not yet widely supported, unfortunately.

The upcoming JPEG Part 3 standard defines a file format called SPIFF. SPIFF is

interoperable with JFIF, in the sense that most JFIF decoders should be able to read the

most common variant of SPIFF. SPIFF has some technical advantages over JFIF, but its

major claim to fame is simply that it is an official standard rather than an informal one.

At this point it is unclear whether SPIFF will supersede JFIF or whether JFIF will

remain the de-facto standard. IJG intends to support SPIFF once the standard is frozen,

but we have not decided whether it should become our default output format or not. (In

any case, our decoder will remain capable of reading JFIF indefinitely.)

Various proprietary file formats incorporating JPEG compression also exist. We have

little or no sympathy for the existence of these formats. Indeed, one of the original

reasons for developing this free software was to help force convergence on common,

open format standards for JPEG files. Don’t use a proprietary file format!

TO DO

The major thrust for v7 will probably be improvement of visual quality. The current

method for scaling the quantization tables is known not to be very good at low Q values.

We also intend to investigate block boundary smoothing, “poor man’s variable

quantization”, and other means of improving quality-vs-file-size performance without

sacrificing compatibility.

In future versions, we are considering supporting some of the upcoming JPEG Part 3

extensions --- principally, variable quantization and the SPIFF file format.

As always, speeding things up is of great interest.

Please send bug reports, offers of help, etc. to [email protected].

■ About PNG Reference Library

libpng versions 1.2.6, August 15, 2004, through 1.2.29, May 8, 2008, are Copyright (c)

2004, 2006-2008 Glenn Randers-Pehrson, and are distributed according to the same

disclaimer and license as libpng-1.2.5 with the following individual added to the list of

Contributing Authors

Cosmin Truta

libpng versions 1.0.7, July 1, 2000, through 1.2.5 - October 3, 2002, are Copyright (c)

2000-2002 Glenn Randers-Pehrson, and are distributed according to the same disclaimer

and license as libpng-1.0.6 with the following individuals added to the list of

Contributing Authors

Simon-Pierre Cadieux

Eric S. Raymond

Gilles Vollant

and with the following additions to the disclaimer:

There is no warranty against interference with your enjoyment of the library or

against infringement. There is no warranty that our efforts or the library will fulfill

any of your particular purposes or needs. This library is provided with all faults,

and the entire risk of satisfactory quality, performance, accuracy, and effort is with

the user.

libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are Copyright (c)

1998, 1999 Glenn Randers-Pehrson, and are distributed according to the same

disclaimer and license as libpng-0.96, with the following individuals added to the list of

Contributing Authors:

Tom Lane

Glenn Randers-Pehrson

Willem van Schaik

Andreas Dilger Distributed according to the same disclaimer and license as libpng-0.88,

with the following individuals added to the list of Contributing Authors:

John Bowler

Kevin Bracey

Sam Bushell

Magnus Holmgren

Greg Roelofs

Tom Tanne r

1996 Guy Eric Schalnat, Group 42, Inc.

For the purposes of this copyright and license, “Contributing Authors” is defined as the

following set of individuals:

Andreas Dilger

Dave Martindale

Guy Eric Schalnat

Paul Schmidt

Tim Wegner

The PNG Reference Library is supplied “AS IS”. The Contributing Authors and Group

42, Inc. disclaim all warranties, expressed or implied, including, without limitation, the

warranties of merchantability and of fitness for any purpose. The Contributing Authors

and Group 42, Inc. assume no liability for direct, indirect, incidental, special, exemplary,

or consequential damages, which may result from the use of the PNG Reference Library,

even if advised of the possibility of such damage.

Permission is hereby granted to use, copy, modify, and distribute this source code, or

portions hereof, for any purpose, without fee, subject to the following restrictions:

1. The origin of this source code must not be misrepresented.

2. Altered versions must be plainly marked as such and must not be misrepresented

as being the original source.

3. This Copyright notice may not be removed or altered from any source or altered

source distribution.

The Contributing Authors and Group 42, Inc. specifically permit, without fee, and

encourage the use of this source code as a component to supporting the PNG file format

in commercial products. If you use this source code in a product, acknowledgment is not

required but would be appreciated.

■ About zlib Library

This software is provided ’as-is’, without any express or implied warranty. In no event

will the authors 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.

Jean-loup Gailly Mark Adler

[email protected] m[email protected]

If you use the zlib library in a product, we would appreciate *not* receiving lengthy

legal documents to sign. The sources are provided for free but without warranty of any

kind. The library has been entirely written by Jean-loup Gailly and Mark Adler; it does

not include third-party code.

If you redistribute modified sources, we would appreciate that you include in the file

ChangeLog history information documenting your changes. Please read the FAQ for

more information on the distribution of modified source versions.

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