Week 5 Required Readings

1.)You Tube and Libraries

This article expounds on positive uses of YouTube (its not just for uploading videos of teenagers beating each other up). With a free account a library could open the eyes of their patrons to all of the services they offer. They would be able to show people how resources can be accessed, at all hours of the day and night. If its 2AM and a student needs help on learning how to use a database, its there even if the reference librarian is not. It would benefit visual learners as well as night owls.

However, I've never been able to get a youtube video to run smoothly, start to finish. So if you have an impatient patron, they may not wait to watch the entire video (you can't please everyone). Its still an interesting idea that seems to be have been successfully used at libraries. However, when checking the citations the video for the "Library Mystery Tour" is no longer there. When checking joemnscu's profile, the user hasn't logged in for ten months. "How to Find the Reference Desk" link no longer works as well. Where did the videos go(granted I didn't do a search for the video title)?

2.) Imaging Pittsburgh - http://www.firstmonday.org/issues/issue9_5/galloway/index.html
I have used this collection before, I find it fascinating to see all of the old pictures of Pittsburgh and to be able to visually see how a street or community has changed. It is really a fabulous collection, if you haven't played around with it, I suggest you do. http://digital.library.pitt.edu/pittsburgh/

It is a collection of images that are held by the University of Pittsburgh, Carnegie Museum, and the Western PA Historical Society. It lets users search across these collections. Searches can be conducted by keyword, explore by time period, location, collection, and you can even order reproductions, which I think are affordable.

The differences of opinion with the three organizations take on cataloging was interesting. It reminded me of the differences in metadata.

"Our museum friends tend to view their image collections as works of art with intrinsic value as a photograph. The academic archives tend to view their image collections for utilitarian purposes with minimal description, while the historical society’s practice has been to provide contextual information that not only describes the image, but informs the reader about the history and impact of an area or person depicted by the image. All this is to say that it has taken time to build a common dialogue for discussing critical elements of the project."

The way they have dealt with the copyright issues of the images I thought was creative. If you need to really use an image you can contact the institution it is from just to make sure you are not violating a copyright.




3. Data Compression - Wikipedia Data is stored in fewer bits by using compression. Examples: zip files or stuffit files. The person sending the data and the person receiving the data need to have the same type of program for decompressing the data.
The next article goes into more detail on the specifics of compression.

I make no guarantees that the notes I have taken are correct.

4.) Data Compression Basics
Part 1
This is how you get more information to travel across the same space as though its less information. Acronyms are an example of compression. For example, MLA stands for the Medical Library Association. This is lossless compression, the item is compressed and then decompressed, thus resulting in the same image.

RLE (Run Length Encoding) - is one way to compress data. It is useful for images that have only a few colors in them. It does not work very well with text except in case studies. It would increase the size of a file instead of shrinking it.
When talking about the use of RLE for images with colors, if you have ever worked with Adobe Illustrator or any other program that lets you "mix" colors using numbers, the compression as so many parts of color x,y,and z makes sense to me.

The Lempel-Ziv Compressor - this works like using an acronym in professional writing. You only need to define an acronym once so you don't have to keep repeating it. After you have identified the American Library Association as the ALA, you can continue to refer to it as the ALA through out your writing. This compressor works similarly, it replaces repeated data. The LZ compressor wants to eliminate redundancy.

Entropy Coding - shorter codes are assigned to common data elements and longer codes are assigned to those that are not common
Huffman Coding: each code has its own unique beginning - this eliminates the need for a special marker
Arithmetic Coding: data is coded between the numbers 0.0 and .1. It works using percentages.

Prediction and Error Coding: Pictures usually have a slow change in colors at the level of the pixels. So this compression stores the error, by what it thinks the next color should be.

Part 2
Lossy compression of Stills and Audio: Your original object will not be the same after the object is decompressed. It preserves perceptible information.

If an object is decompressed and then recompressed several times with a lossy compressor, it will eventually cause a noticeable difference between the original and multiply compressed image.

I think an example of this is when you upload a picture to facebook or flickr, but when you download it, its quality is crappy.

The writers on these compression programs have to take into consideration the range of human sensation and perception. A computer doesn't know which part of a sound recording is more important, the person talking or the noise of the tape.

Part 3
Video Compression:
Video has to be compressed because it would take a long time to load and view.