Week 5 Readings

1.) Wikipedia Article - Data Compression

I really like the fact that we start off each weeks readings with a Wikipedia article - they provide a good overview for what we will read about more in depth later. Again, this article was a good overview though it did not go as in depth as some of the other ones.

Data compression is also known as source coding. It is the process of encoding information using fewer bits. Both the sender and the receiver must understand the coding schema - you must know how to decode it. Data compression is useful because it reduces the consumption of expensive resources (such as hard disk space or bandwidth).

There are two different kinds of data compression - loseless and lossy. Loseless compression uses statistical redundancy to represent data more concisely and without error. It is used more for text-based compression. Lossy data compression is possible if some fidelity loss is acceptable. Lossy compression "rounds off" some of the less important information. This is used more with visual or audio data - where some loss of quality is okay and you still get the same basic idea.

2.)Data Compression Basics

As blackboard said these were long documents but did a good job in covering the basics of many different kinds of data compression. The articles were technical enough, but not so technical that you couldn't understand them. It did a good job of balancing the technical jargon, while still explaining the concepts to you in plain language.

I really liked the articles definition of data compression, it "lets you store more stuff in the same space, and it lets you transfer the stuff in less time, or with less bandwidth." This is a defintion anybody can understand, and does a good job of summing up what data compression is.

This article had way to much information to do a good job of summing it up in this blog, so I'm just going to point out the one thing I found the most interesting/didn't know before reading this article. I didn't realize that moving pictures are acutally just a sequence of individual images. So to compress them you compress each image individually (most likely into a JPEG). To replay them the playback device must be able to decompress the images quickly enough to display them at the required speed.

3.)Galloway Imaging Pittsburgh

This article was very informative and provided a lot of useful real world information for future archivists and librarians. The article was about a 2002 grant Pitt received to provide online access to photographic collections. Over 20 collections from 3 different instituions provided for over 7,000 images being placed online. On the website that the images are at you can do a keyword search, read about the collections and their contents, explore the images by time, place, or theme, and order image reporductions.

What I liked most about the article, and what was most informative, was the real world problems they encountered, and how they dealt with them. Although a lot of the problems they encountered were due to the fact that this project was a collaboration of three institutions the problems and solutions were very informative. Selection will always be a big problem with grants and projects of this nature. They ran into this, especially with split collections. They also ran into metadata challenges because each individual institution wanted a specific kind of metadata for their images. Copyright issues were also a problem, and I liked their solution. They provide a generic copyright warning and also an individual one specific to each image and institution, to covery all their basis.

I took a look at the website that the images are displayed on and it is very well done and has an enormous amount of very informative and cool pictures. I especially liked the sections on maps. Overall, this was a very good article and very informative for future archivists.