Notes on Data Compression
Based on the readings the main advantage for data compression or source coding is that it lets you store more stuff in the same space and it lets you transfer that stuff in less time or with less bandwidth. An example of this is the recent Flicker assignment where we were asked to save pictures as thumbnails and screen size. There are 2 types of data compression. We are most familiar with the lossy method, where recorded information is not guaranteed to be exactly identical, JPEG and MP3 are examples of lossy data compression. Lossless data compression is when the recorded information is guaranteed to be exactly identical to the original compression method. Lossless method is used to optimize disk space in office computers or better bandwidth connection in a computer network.
As librarians it is important to understand the characteristics of data compression when planning to digitize a special collection in a library. First and foremost, a technological infrastructure has to be in place in order to support and access the digital collections. For users or patrons to view compressed data images (jpeg and mpeg) the network or their own computer, must be equipped with large memory storage and optimal bandwidth to download and view files. In order to view a compressed file, it has to be decompressed. This may disrupt applications the user may have open and create an inconvenience, resulting in not accessing the collection. While data compression offers the advantage of storing more stuff in the same space, it is implied that the end-user or a library network has the technological capability and resources to view these files.
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2 comments:
Thank you for this posting. I had not heretofore thought that hardware was needed for both compression and decompression. I now understand that while it is one thing to compress the data, it is entirely another to have decompression/reading capacity.
You brought up a good point about who can actually use compressed data once it's been compressed. I hadn't considered the memory needed by the enduser to download and decompress previously compressed data. I suppose I had only thought of this on an individual level (compressing data for personal use), but the issues of compatibility and sharing are significant as well.
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