Compression is likely to be effective only if you use 1024 resolution (really, any resolution higher than 256, but 1024 often is the only other choice) to acquire your data. That's because most of the bits of the higher order bytes are zero. If you use 256-resolution to collect data, compression likely will make the files a bit larger. You get the smallest files using 256-resolution to collect your data to begin with. Higher resolution usually is overkill, but you might need it to resolve closely spaced sharp peaks, or if you will be doing some kind of after-the-fact transformation of the data (e.g. to log scale). Neal Maciej Simm wrote: > > Since we recently discussed backups/CD writers etc, I thought I > would share some of my observations with compression in regards to > storage: > > *** EXAMPLES *** > > #1 > "january 2001 cytokines" folder: 1014 items, 334.7 MB on disk > and after compression: > january 2001 cytokines.zip : 1 item , 24.2 MB on disk > > #2 > "burst tests" folder: 1645 items, 593.1 MB on disk > and after compression: > burst tests.zip : 1 item , 227.7 MB on disk > > These are the extreme ranges of my results so far, showing a range of > 62% to 93% decrease in size. > > some of my flowjo workspaces shrunk from 2 megs to 30 kilobytes. > > *** PROS *** > > 1. more cost effective storage > 2. more data accessible per volume.. ex one year fitting on one disc > as opposed to three etc... > 3. compatibility - once zipped, files can be moved to PC's and stored > that way and the contents of the zip file are still "mac" > 4. no buffer underrruns in CD-writing - a bunch of small files is > much more likely to create buffer underrruns during burning process, > esp. at high speeds (12, 16X) > > *** CONS *** > 1. in event of disk scratch - you loose more data, thus duplicates > are a must > 2. depending on the speed of the computer, it takes some time to > "decompress" the files (the above mentioned burst test folder took 5 > minutes do compress on a G3-400, it takes less time to decompress) > > if anyone else has something to add to the topic on compression feel > free to post it on the group I'd be interested to learn new tricks. > > maciej > > ===== > `---------------------------------------------` > | Maciej S. Simm | 525 E 68th Street | > | Research Technician | Room N-805 | > | Cornell Medical Center | Tel. 212.746.3428 | > `---------------------------------------------` > |www.cd4cd8.com | 917-734-6280 | AIM - XsimmX | > `---------------------------------------------` > > __________________________________________________ > Get personalized email addresses from Yahoo! Mail - only $35 > a year! http://personal.mail.yahoo.com/ -- Neal Benson University of Florida nbenson@ufl.edu
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