n8541751@unicorn.cc.wwu.edu (Where there is darkness, light) (03/06/91)
Does anyone know where to get a document describing the file format for JPEG? Is it even available? An ftp source would be ideal. Sorry if this is a Frequently Asked Question; judging by the recent postings in comp.graphics it doesn't appear to be a Frequently Answered Question at least. Thanks! Kris. -- Kriston M. Bruland | . . . . . . . . . . n8541751@unicorn.cc.wwu.edu | . . . . . . . . . 8541751@nessie.cc.wwu.edu | . . . . . .
rkunenbo@cs.ruu.nl (Ronald Kunenborg) (03/06/91)
In <1991Mar6.002423.3038@unicorn.cc.wwu.edu> n8541751@unicorn.cc.wwu.edu (Where there is darkness, light) writes: >Does anyone know where to get a document describing the file format for JPEG? >Is it even available? An ftp source would be ideal. > >Sorry if this is a Frequently Asked Question; judging by the recent postings >in comp.graphics it doesn't appear to be a Frequently Answered Question at >least. It is getting frequently asked, but I haven't seen an answer yet. And now for something completely different: Does anyone know the ALGORITHMS for JPEG/MPEG compression and decompression ? If you have descriptions or know where to get them, *PLEASE* could you post/ email them ? >Thanks! Many (MANY!) thanks from me too! >Kris. -- Ronald Kunenborg, Victoriestraat 3, 3815 ML Amersfoort, The Netherlands (rkunenbo@praxis.cs.ruu.nl) "If we must die, let it not be like hogs... Like men we'll face the murderous, cowardly pack, Pressed to the wall, dying, but fighting back!" - Claude McKay, 1919. -- ---------------------------------------------------------------------------- Ronald Kunenborg, Victoriestraat 3, 3815 ML Amersfoort, The Netherlands (rkunenbo@praxis.cs.ruu.nl)
tgl@g.gp.cs.cmu.edu (Tom Lane) (03/07/91)
>>Does anyone know where to get a document describing the file format for JPEG? >>Is it even available? An ftp source would be ideal. > > Does anyone know the ALGORITHMS for JPEG/MPEG compression and decompression? As far as I know, the JPEG spec is not available on-line anywhere. (If anyone finds out different, please let me know!) You can order a paper copy of the spec from the ANSI X3 secretariat. Write to: Attn: JPEG Draft Technical Specification X3 Secretariat: Computer and Business Equipment Manufacturers Association 311 First Street NW, Suite 500 Washington, DC 20001-2178 Enclose a check for $8.00 made out to X3 Secretariat. Say somewhere in your letter that you want the document for review and comment. However, I don't recommend that everybody order a copy. For one thing, they seem to have just one overworked secretary Xeroxing these copies. For another, the JPEG algorithm is not simple nor easy to implement. Unless you already know something about color space conversion, discrete cosine transforms, Huffman and arithmetic coding, you'll not learn much from reading the draft spec. For a third thing, the draft spec actually defines a family of compression algorithms, not a specific file format. If you try to implement from just the draft spec, you will most likely find yourself unable to exchange compressed files with other implementations. I am running a group of volunteers that is writing a free, portable implementation of the JPEG algorithm. We expect to release something in a couple months' time. (On the other hand, I said that a couple months ago, so don't hold your breath.) I recommend that everybody sit tight and wait for our code, rather than trying to build your own versions. If you'd like to help out, we could still use some more volunteers. -- tom lane Internet: tgl@cs.cmu.edu BITNET: tgl%cs.cmu.edu@cmuccvma
hsi@netcom.COM (Handmade Software) (03/07/91)
In article <1991Mar6.002423.3038@unicorn.cc.wwu.edu>, n8541751@unicorn.cc.wwu.edu (Where there is darkness, light) writes: > > Does anyone know where to get a document describing the file format for JPEG? Contact: X3 Secretariat Computer and Business Equipment Manufacturers Institute 311 First Street NW, Suite 500 Washington, DC 20001-2178 The last time I checked they were charging $8.00 for the JPEG-8-R8 draft. allan -- Handmade Software, Inc. 15951 Los Gatos Blvd, Suite 7 Los Gatos, CA 95032 hsi@netcom.com or {apple|claris}!netcom!hsi