armfield@nprdc.navy.mil (Sylvia Armfield) (07/10/90)
I need to know how to identify the following file formats:
IGES
DXF
CGM
CITT FAX4
EPS
PCX
TIFF
Please email me directly if you have any information.
Thank you,
Sylvia Armfield armfield@nprdc.navy.mil (Sylvia Armfield) (07/11/90)
I still haven't figured out how to identify the following file
formats: IGES
CGM
CITT FAX4
PCX
If anyone knows what the first characters are in these file formats that
would determine a file to be of one of those types, I'd appreciate the
information. Please email me directly.
Thank you,
Sylvia Armfield
graham@advsys.UUCP (Graham Underwood) (07/12/90)
In article <8437@arctic.nprdc.arpa> armfield@nprdc.navy.mil (Sylvia Armfield) writes: > > I still haven't figured out how to identify the following file >formats: > CITT FAX4 CCITT [sic] Group 4 is not a file format, it is an image compression standard. The encoded data is therefore dependent on the image you are compressing and there is no way to determine that it is Group 4 data. (Other than starting to decompress it and seeing if you get something inteligible - but thats probably for comp.ai enthusiasts). Group 4 data alone does not contain sufficient information for you to decode it - e.g. you have to know the pixel width of the image. You will probably find that the Group 4 data is wrapped up inside a file format such as TIFF which enables the other information to be specified. Graham.
darcy@druid.uucp (D'Arcy J.M. Cain) (07/13/90)
In article <8437@arctic.nprdc.arpa> armfield@nprdc.navy.mil (Sylvia Armfield) writes: > I still haven't figured out how to identify the following file formats: > CGM > There is more than one type of CGM file. I can help you out with the clear text encoding and the binary encoding. The other encoding is character. It is described in ISO 8632-2. In any case all CGM files start with the same thing, the BEGIN METAFILE statement. The only difference is in how this element is encoded. In clear text encoding the element is simply the ASCII string "BEGMF". In binary encoding you have to read in the first two bytes as a word. The MSB is followed in the file by the LSB. This word is bitmapped to include the following information: 15 - 12: Element class 11 - 5: Element ID 4 - 0: Parameter list length BEGIN METAFILE is a "Delimiter Element" making it class 0. The element ID within that class is 1. The parameter list length is variable so it must be ANDed out when comparing. The bit pattern is then: 0 0 0 0 0 0 0 0 0 0 1 x x x x x To check it simply AND the word with 0xffe0 and compare it with 0x0020. In reading the standard I get the impression that it is actually legal to add padding characters (nulls) to the beginning of the file. I rather doubt that anyone would actually do this but it may be appropriate to read in words till a non zero word is read and compare this word. You can read in full words since all elements are constrained to start on a word boundary. If you want the full description of the CGM format it is available from ANSI as the following ISO standards: ISO 8632-1 Functional specification ISO 8632-2 Character encoding ISO 8632-3 Binary encoding ISO 8632-4 Clear text encoding HTH -- D'Arcy J.M. Cain (darcy@druid) | Government: D'Arcy Cain Consulting | Organized crime with an attitude West Hill, Ontario, Canada | (416) 281-6094 |
27003_1531@uwovax.uwo.ca (Chris Baldock) (10/20/90)
Hi. I'm looking for some info on graphic file formats.. Particularly: WMF (Windows Metafile IBM PC) CGM (Colour Graphics Metafile) CDR (Coral Draw Files) or where I can find utilties to do conversions... Thanks in Advance, Bill McLean SA_BILL@VAXI.SSCL.UWO.CA mclean@obelix.gaul.csd.uwo.ca
alpowell@images.cs.und.ac.za (03/13/91)
There seems to be a lot of interest in the various file formats used by various drawing programs. Why doesn't some helpful person summarise the various formats (TIFF, GIF, PCX, etc.) information (eg. what is data and what is header, what sort of compression is applied to the data (if at all), etc) and repost it ? I know that many people (myself included) would find it most useful. P.S. Some of us don't have access to anonymous ftp, so that avenue is not open to us, hence this posting. Thanks, Al.
adrianho@barkley.watt.berkeley.edu (Adrian J Ho) (03/14/91)
In article <1991Mar12.191456.9336@images.cs.und.ac.za> alpowell@images.cs.und.ac.za writes: >There seems to be a lot of interest in the various file formats used >by various drawing programs. Why doesn't some helpful person summarise >the various formats (TIFF, GIF, PCX, etc.) information (eg. what is data >and what is header, what sort of compression is applied to the data (if >at all), etc) and repost it ? Perhaps because most people *don't* want summaries -- some formats (eg. GIF) use coding algorithms that are usually difficult to summarize in a useful manner. Others are so complex that you'd usually end up extracting the full text for these. Multiply by the number of different file formats supported by drawing programs, and I think you'll end up with one *long* posting. That's only the beginning -- there will *definitely* be repeated requests for reposts (sounds like ~30% of all USENET sites expire articles after 24 hrs, and >30% of net.news is read >2 days after posting 8-). I think you can see what I'm getting at: an incredible amount of bandwidth wasted for a single document. Oh, and how about those requests to "please add format FuBaR to the list"? I don't envy the person who takes this task up. (And after saying all that, I must be nuts for continuing to say that I'm willing to give it a shot. Stay tuned. 8-) Try the format archives at titan.rice.edu (128.42.1.30) (directory public/graphics.formats -- info courtesy of Jef Poskanzer's comp.graphics FAQ, posted every week). You'd probably get more useful info from the full specs. >P.S. Some of us don't have access to anonymous ftp, so that avenue is >not open to us, hence this posting. But most sites certainly have access to e-mail facilities, and there are such things as mail-FTP servers. To quote again from the FAQ (and please, folx, let's show appreciation for Jef's efforts by *reading* it -- 24-hr news expiry notwithstanding): % 13) How to FTP by email. % There are a number of sites that archive the Usenet sources newsgroups % and make them available via an email query system. You send a message % to an automated server saying something like "send comp.sources.unix/fbm", % and a few hours or days later you get the file in the mail. % There are also a couple of sites that will perform general FTP retrievals % for you in response to a similar mail query. For information on using % one of them, send a message like this: % To: info-server@cs.net % request: info % topic: help-ftp % request: end % (NOTE: this server is currently "down for repairs". No estimate on when % or if it will return.) % And for info on another one, send this: % To: bitftp@pucc.bitnet % help % Please be considerate, and don't over-use these services. If people % start using them to retrieve hundreds of megabytes of GIF files, they % will probably disappear. Take note of that last paragraph and don't abuse these facilities -- they cost the providers lots of MONEY. Good Luck! ----------------------------------------------------------------------------- Adrian Ho, EECS (pronounced "eeks!") Dept. Phone: (415) 642-5563 UC Berkeley adrianho@barkley.berkeley.edu Domain: sesame-street (telly,bigbird,snuffy,oscar,kermit,bert,grover,barkley) Favorite expression: "There's no business like monkey business."