Thursday, May 22, 2008

What format do you use when you compress files

PKZIP 2.04g for DOS, circa 1993.I have always by default used the ZIP file format whenever I have needed to compress files. Never gave it a second thought as I have been using ZIP files for archiving since the days of PKZip/UnZip (at least 17 years).

That was until a friend of mine (Josh Morey) from work told me to use *.7z. And he pointed me at the following page to prove his point Comparison of compression methods.

Sure enough it turns out 7z leads to higher compression ratios. (For example on a LAS file - a LiDAR point cloud containing binary data - the original file was about 73 Mb. The ZIP format lead to a compressed size of 40mb and the 7Z format lead to a file size of 29mb). It does seem to run slower than when I zipped the file, but to me compression ratios are more important that processing speed.

His recommendation for software to use - 7 Zip and iZarc. I like 7 Zip, as it has a good set of context menu options - which is important to me (I hardly use the full UI to perform my compression and decompression work). He likes iZarc as it has a release that is portable and can be run off a USB drive.

Whatever you choose - bottom line - if you have been using ZIP by default, then its time you took a look at the newer compression algorithms.

Thanks to Josh on setting me straight on the path to reduced bits.

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