Compression Software

Stephen Modena nmodena at unity.ncsu.edu
Sun Dec 8 18:05:08 EST 1991


In article <01GDRFJPLP680005LN at BIOMED.MED.YALE.EDU> ALSOBROOK at BIOMED.MED.YALE.EDU writes:
>From:	IN%"harper at convex.csc.FI"  4-DEC-1991 04:52:00.39
>To:	IN%"software at genbank.bio.net"
>CC:	
>Subj:	RE: Compression Software
>
>
>>In <1991Dec4.043820.7565 at alw.nih.gov> donnel at helix.nih.gov (Donald A. Lehn) writ
>>es:
>  
>>>       I'm afraid that you will be hard pressed to compress these files.
>>>I'm pretty sure that they are TIFF files and as such are about as
>>>compressed as they can get.  (You can compress the header info though and
>>>that is how you squeezed the 3Mb out of the file.)
> 
>>This is also true for GIF files, they are already compressed, so there is
>>not much point trying to compress them further... and in some cases if
>>you do try it you will get a BIGGER file than you started with.
> 
>>>--
>>>Donald A. Lehn, Ph.D.                      Phone: (301) 496-2885
>>>Bldg.37 Rm 3D20                            FAX:   (301) 496-8419
>>>National Cancer Institute / NIH            Email: donnel at helix.nih.gov
>>>Bethesda MD 20892
>--
>>   Rob Harper                     /   E-mail:          harper at convex.csc.fi
>>   Finnish State Computer Centre  /   Molbio/software: harper at nic.funet.fi
>>   P.O. Box 40, SF-02101 Espoo    /   Telephone:       +358 0 457 2076
>>   Finland                        /   Fax:             +358 0 457 2302
>
>There is a program available for PCs running DOS -- the program is called JPEG;
>it compresses  GIF files (not sure about TIFF) -- the compession ratio depends
>on how much  quality (i.e. resolution) you want retained. It easily compresses
>by a factor of two with very little image degradation. I don't know what other
>platforms it can run on, or if there are any file size limits, but I will post
>the name/address of the developer (it's shareware, so you only pay if you want
>to keep it, and a very reasonable price at that!).
>
>****************************************************************************
>*                                       |                                  *
>* John Alsobrook                        |    Never ask a question whose    *
>* Child Study Center                    |    answer you are not prepared   *
>* Yale University School of Medicine    |             to hear.             *
>*--------------------------------------------------------------------------*
>*                  bitnet: alsobrook at yalemed.bitnet                        *
>*               internet:alsobrook at biomed.med.yale.edu                     *
>*--------------------------------------------------------------------------*
> 

Well, the alt.sex.* fora have plenty of traffic in GIFs that have been
JPEG'd....and the compression is typically 4:1....that is, a 30K *.jpg
file of decompresses to a 120K *.GIF file.  The ratio varies according
to a Q-factor set upon compression of the original.

And I'd say "wake up" to this JPEG algorithm, Folks, 'cuz I just read in
INFO WORLD (or was it PC Week) that Chips & Technology and another
company are producing a chip set that will do JPEG
decompression/decompression on the fly for MultiMedia (you know, movies
on your PC screen).

So within 1 year GIF/TIFF and others will become a gross waste of
bandwidth for transmission of serious images.

Have a nice day!   :^)




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