lwv27@CAS.BITNET (08/02/90)
Compuserve has made available in their Graphics Support Forum a new
GIF89a document which details the current standards. Here is a
bit of info from it (I wasnt able to get it downloaded due to
system problems). It is available in Lib 14, the Misc Util & Code library.
[76703,704]
GIF89A.ARC/binary 01-Aug-90 31637 Accesses: 5
Title : CompuServe's Graphic Interchange Format (tm)- 89a
Keywords: GIF GRAPHICS 89A GIF89A DOCUMENT SPECIFICATION COMPUSERVE ARC
The official ARC version of CompuServe, Incorporated's Graphic
Interchange Format (tm), 89a edition.
The Graphics Interchange Format (tm) is the copyright property of
CompuServe, Incorporated.
CompuServe hereby grants a limited, non-exclusive, royality-free license
for the use of GIF. For more information, see the licensing section of
the document.
[76703,704]
GIF89A.DOC 01-Aug-90 85478 Accesses: 1
Title : CompuServe's Graphics Interchange Format (tm)-89a
Keywords: GIF GRAPHICS COMPUSERVE GIF89A 89A DOCUMENT SPECIFICATION ASCII
The official ASCII version of CompuServe, Incorporated's Graphic
Interchange Format (tm), 89a edition.
The Graphics Interchange Format (tm) is the copyright property of
CompuServe, Incorporated.
CompuServe, Incorporated hereby grants a limited, non-exclusive,
royality-free, license for the use of GIF. For more information, see the
licensing section of the document.
An extract from the cover sheet of the document:
----
APPLICATION EXTENSION BLOCK - APPLICATION IDENTIFIER
There will be a Courtesy Directory file located on CompuServe in the PICS
forum. This directory will contain Application Identifiers for Application
Extension Blocks that have been used by developers of GIF applications.
This file is intended to help keep developers that wish to create
Application Extension Blocks from using the same Application Identifiers.
This is not an official directory; it is for voluntary participation only
and does not guarantee that someone will not use the same identifier.
E-Mail can be sent to Larry Wood (forum manager of PICS) indicating the
request for inclusion in this file with an identifier.
----
Note that Mr Wood's CIS id is [76703,704], thus, you should be able to
contact him directly by addressing internet type mail to 76703.704@compuserve.co
or osu-cis!compuserve.com!76703.704 .
----
The Table of Contents:
Disclaimer................................................................. 1
Foreword................................................................... 1
Licensing.................................................................. 1
About the Document......................................................... 2
General Description........................................................ 2
Version Numbers............................................................ 2
The Encoder................................................................ 3
The Decoder................................................................ 3
Compliance................................................................. 3
About Recommendations...................................................... 4
About Color Tables......................................................... 4
Blocks, Extensions and Scope............................................... 4
Block Sizes................................................................ 5
Using GIF as an embedded protocol.......................................... 5
Data Sub-blocks............................................................ 5
Block Terminator........................................................... 6
Header..................................................................... 7
Logical Screen Descriptor.................................................. 8
Global Color Table......................................................... 10
Image Descriptor........................................................... 11
Local Color Table.......................................................... 13
Table Based Image Data..................................................... 14
Graphic Control Extension.................................................. 15
Comment Extension.......................................................... 17
Plain Text Extension....................................................... 18
Application Extension...................................................... 21
Trailer.................................................................... 23
Quick Reference Table...................................................... 24
GIF Grammar................................................................ 25
Glossary................................................................... 27
Conventions................................................................ 28
Interlaced Images.......................................................... 29
Variable-Length-Code LZW Compression....................................... 30
On-line Capabilities Dialogue.............................................. 33
--
Larry W. Virden
Business: UUCP: osu-cis!chemabs!lwv27 INET: lwv27%cas.BITNET@CUNYVM.CUNY.Edu
Personal: 674 Falls Place, Reynoldsburg,OH 43068-1614
Proline: lvirden@pro-tcc.cts.com America Online: lvirden CIS: [75046,606]clarke@acheron.uucp (Ed Clarke/10240000) (08/03/90)
From article <9008011858.AA28860@jade.berkeley.edu>, by lwv27@CAS.BITNET: > Compuserve has made available in their Graphics Support Forum a new > GIF89a document which details the current standards. Here is a Hmmmm .... do they mention compression in the new document? The LZW code seems to be a violation of the UNISYS patent. Perhaps TIFF would be a better target since the compression method doesn't have to be LZW and the aspect ratio is already defined in the file. I have no strong feelings either way ... -- | Ed Clarke | I prefer not to kill animals. I'm a humanist; I'd acheron!clarke | rather kill a MAN than a snake. | - Edward Abbey (Desert Solitaire)
sigma@pawl.rpi.edu (Kevin J Martin) (09/04/90)
clarke@acheron.uucp (Ed Clarke/10240000) writes: >From article <9008011858.AA28860@jade.berkeley.edu>, by lwv27@CAS.BITNET: >> Compuserve has made available in their Graphics Support Forum a new >> GIF89a document which details the current standards. Here is a >Hmmmm .... do they mention compression in the new document? The LZW >code seems to be a violation of the UNISYS patent. Perhaps TIFF would >be a better target since the compression method doesn't have to be >LZW and the aspect ratio is already defined in the file. What UNISYS patent?! On the algorithm, or the appellation 'LZW' (which is/are the initials of the authors, Lempel Ziv and Welch)? The algorithm is used by more programs than I can count, including ARC, and ZIP so they might be interested in hearing about the patent. -- Kevin Martin ||| sigma@pawl.rpi.edu ||| usergkj1@RPITSMTS.BITNET
davidm@uunet.UU.NET (David S. Masterson) (09/05/90)
In article <S`}%NN^@rpi.edu> sigma@pawl.rpi.edu (Kevin J Martin) writes: clarke@acheron.uucp (Ed Clarke/10240000) writes: >Hmmmm .... do they mention compression in the new document? The LZW >code seems to be a violation of the UNISYS patent. Perhaps TIFF would >be a better target since the compression method doesn't have to be >LZW and the aspect ratio is already defined in the file. What UNISYS patent?! On the algorithm, or the appellation 'LZW' (which is/are the initials of the authors, Lempel Ziv and Welch)? The algorithm is used by more programs than I can count, including ARC, and ZIP so they might be interested in hearing about the patent. Check gnus.discuss. Quite the argument going on over there. -- ==================================================================== David Masterson Consilium, Inc. uunet!cimshop!davidm Mtn. View, CA 94043 ==================================================================== "If someone thinks they know what I said, then I didn't say it!"
fsb@stsim.ocs.com (Steve Brailsford) (09/06/90)
To: sigma@pawl.rpi.edu Subject: Re: New GIF standard available! Newsgroups: comp.graphics In-Reply-To: <S`}%NN^@rpi.edu> References: <9008011858.AA28860@jade.berkeley.edu> <1990Aug2.230752.9471@acheron.uucp> Organization: Online Computer Systems, Inc. Cc: Bcc: Compuserve and the GIF community has heard about the LZW patent for some time now. They are looking into it as far as I know. And yea, there is an awful lot of programs that use that algorithm. Too bad they couldn't have told people they were patenting the thing before a million people started using thinking it was free to use. Everyone's trying to get as many buchs as they can it seems these days, and it's only free if it's on no real use. Steve Brailsford uunet!ocsmd!stsim!fsb