Reading 5 - Jon Good

In Cory Arcangel’s article “On Compression” he discusses the different techniques of image compression.  He presents very understanding examples and metaphors on how compression works.  He also provides the formulas that it takes to create the compression of data.  There are two types of data compression; Lossy and Lossless.

Lossless is the compression of data without losing any information.  Cory's example of how to understand Lossless compression is very interesting.  He states that if a bit of data such as this: 'a a a a a a a a a b a' would be transmitted without compression it would be a larger file size.  Transmitting large amounts of data is slow and expensive.  Now if the file was compressed then it would be able to retain the same information but using less space.  The way the computer can do this is it describes the information in a way that takes less space such as '9a's, one b, and one a'.  It translates to the original data.



Lossy compression actually loses some of the data after compression.  Since there is some loss of data it can not be used for text, or any application that all data is needed.  It is used for images, music, and video.  The way the computer gets away with this is after the file is compressed, it takes away some of the data that our senses can't notice.  Using the same example of before it would say there are just '11a's'. 



I find it very interesting that files can be compressed in this way.  It seems as if the file could have just had all the information needed in the first place.  I now can understand how the JPEG image doesn't have a very high quality of image because of the process the computer goes through to compress the image in to a smaller size.