Data Compression :: essays research papers fc

Data Compression just sounds complicated. Dont beafraid, compression is our good friend for many reasons. It saves hard drivespace. It makes info file aways to handle. It also cuts those immense file downloadtimes from the Internet. Wouldnt it be nice if we could compress all filesdown to just a few bytes? on that point is a limit to how much you can compressa file. How random the file is, is the determining factor to how far it canbe compressed. If the file is all told random and no pattern can be found,then the shortest representation of the file is the file it self. The actualproof that proves this is at the end of my paper. The key to wedge afile is to find round sort of exploitable pattern. Most of this paper willbe explaining those patterns that are commonly used.Null suppression isthe most unmannerly form of data compression that I could find. Basically,it says that if you have different fields that data is in (possibly a spreadsheet), and any of them have only zeros in them, then the program just eliminatesthe data and goes straight from the empty data set to the next.Only onestep up from null suppression is give way Length Encoding. Run length encodingsimply tells you how many of what you have in a row. It would change a setof binary data the likes of 0011100001 into what the computer reads as (2)zeros,(3)ones, (4)zeros, 1. As you can see, it works on the same basic idea of findinga series of 0s (null suppression) and 1s in this case too and abbreviatingthem.Once the whole idea of data compression caught on, more people startedworking on programs for it. From these people we got some new premises towork with. Substitutional encoding is a big one. It was invented jointlyby two people Abraham Lempel and Jakob Ziv. Most compression algorithms (bigword meaning about program) using substitutional encoding start with LZfor Lempel-Ziv. LZ-77 is a really neat compression in which the programstarts off just copying the source file over to the new targe t file, but whenit recognizes a phrase of data that it has previously written, it replacesthe second set of data in the target file with directions on how to get tothe first occurrence of it and copy it in the directions place. This is morecommonly called a sliding-window compression because the focus of the programis always sliding all nigh the file.LZ-78 is the compression that mostpeople have in their homes.