Notes for Week 3 Required Readings

The following two reading materials gives me a general idea about data compression and helps me understand some basic features about compression and ways to approach it.

Data Compression.

http://en.wikipedia.org/wiki/Data_compression

Data compression basics

http://dvd-hq.info/data_compression_1.php

• Compare Lossless & Lossy

Lossless compression	identifying and eliminating statistical redundancy	No information lost	Reversible
Lossy compression	identifying unnecessary information and removing it	Information lost is acceptable	Non-reversible (not sure)

• Why data needs to be compressed?

Help reduce resource usage → data storage space; transmission capacity

• Factors need to be considered when design a data compressing scheme:

The degree of compression;

The amount of distortion introduced; 

The computational resources required to be compressed and uncompressed. 

• Uses

       [Audio]

       -Lossless: can decompress to an exact duplicate of the original one;

                 unable to attain high compression ratios

                 (complexity of waveforms & rapid changes in sound form);

--Combination: allows stripping the correction to easily obtain a lossy file

--Lossy: achieves far greater compression (discarding less-critical data);
             audio quality suffers when decompressed and recompressed
             (unsuitable for professional audio engineering applications but       
             popular with end users)

       [Video]
       -spatial image compression & temporal motion compensation;

--majority: use lossy compression

       [Image]
       -improves the compression ratios by: channel sorting; reducing number of colors.

       -quality: decrease

        The following reading materials gives me a practical example related to data compression, especially in image field.

Edward A. Galloway, “Imaging Pittsburgh: Creating a shared gateway to digital image collections of the Pittsburgh region” First Monday 9:5 2004 http://firstmonday.org/htbin/cgiwrap/bin/ojs/index.php/fm/article/view/1141/1061

        This article introduces a project (1 Nov. 2002 to 31 Oct. 2004) about create a gateway to visual image collections in the Pittsburgh region, including the grant partners, the image collections, the purpose, the progress, the challenges, the solutions, the outcomes and impacts.

        Among all the information of this "Imaging Pittsburgh" project, the challenges they've encountered and the solutions they've came up with are parts that interests me most.

• Communication challenges & solutions

   Challenges:

    -A lack of dialogue outside the meetings;

    -Little or no communication on the listserv and the projects Web site;

    -Different missions and institutional cultures among partners.

   Solutions:

    -Project e-mail distribution list;

    -A web site for posting documentation;

    -Monthly meetings;

    -Build a common dialogue for discussing critical elements of the project.

•  Selection challenges & solutions

    Challenges:

    -Scanning capabilities such as size, format condition, etc.

    -Ensure the collection as a whole is balanced;

    -Split collections

         Solutions:

              -The use of subject headings;

              -Curators from both institutions select images and make decisions 
             --together.

• Metadata challenges

   Challenges:

    -Wide metadata needs VS. Local needs;

    -Choosing controlled vocabulary;

    -The use of dates.

   Solutions:

    -Set eight Dublin Core elements, while each institution can include     
    -additional fields;

    -Use controlled vocabulary terms from LCSH when cataloging images;

    -Create two date fields, one for computer sorting, one for users.

• Workflow challenges

   Challenges:

    -Creating a workflow to get the images through numerous processing 
    -steps;

    -Image quality;

    -The creation and use of identical software applications or field 
    -structure due to the unique set of partners.

   Solutions:

    -Share different workflows and ideas, reconsider and incorporate new 
     ones;

    -A minimum for DRL, a higher quality for other purposes (depends on 
     the institution itself);

    -Insisted that the appropriate and necessary metadata fields be able 
    -to be exported.

• Web site development challenges

   Challenges:

    -Develop consistent copyright and permission statements;

    -Best way to communicate with users;

    -Emphasizing access to the collection as a whole, while also 
     maintaining the individual identity of each collection;

    -The limitations of the DLXS Image-Class middleware and internal 
    -resources

   Solutions:

    -Two-fold strategy → developed a generic copyright; each individual 
    -image’s metadata contains a copyright field;

    -Develop a sophisticated e-mail system, while continue to using the 
     current e-mail distribution list;

    -Plan on conduction an online survey, and create OAI records.

•  Avenues for exploring

    Challenges:

          -Develop creative ways to help users explore the collections.

    Solutions:

    -Cataloging the images (via time, place, and theme);

    -Clickable city map.

        The following article provides an eye-opened way for libraries to share their resources and services, especially libraries’ instruction and training.

Paula L. Webb, YouTube and libraries: It could be a beautiful relationship C&RL News, June 2007 Vol. 68, No. 6

http://crln.acrl.org/content/68/6/354.full.pdf

• Advantages:

--      The most popular internet television or video distribution site;

--      Easy to get started;

--      Provide easy access to guides anywhere;

--      Notifications & RSS;

--      Good for visual learners.

• One question:

        The article says “Be very careful about what you upload onto YouTube.” This implies YouTube’s copyright regulations. However, what is the specific ways for them to identify whether the video is original or it is violated the copyright? In other words, how to ensure the copyright if a library upload a video about the information resources they have?