Computer/Technical Jargon

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Lossless: A data compression technique that preserves all the data. See also lossy. Because some data is not discarded, lossless compressed files are always bigger than lossy compressed files. An example of lossless compression are ZIP files. Some HD DVD's and Blu-Ray movies have lossless audio tracks. High-defination quality audio benefits greatly from lossless audio, whereas CD quality audio sounds almost as good using lossy audio, listed below.

Lossy: A data compression technique that throws away some data. The greater the compression, the more data that is discarded. See the pictures below of baby Kaylin. Each is progressive compressed more, with more and more data thrown away.


Uncompressed 39.7 KB	20% compressed 7.26 KB (82% smaller)	45% compressed 3.96 KB (90% smaller)	90% compressed 1.70 KB (96% smaller)	99% compressed 0.92 KB (98% smaller)

You can see the picture gets worse the more it is compressed. Look careful at the 20% compress image compared to the uncompressed image. Specifically, look carefully at the top of the hair and notice it is a little fuzzier. Other details are little fuzzier and the colors are not as crisp. Although these pictures don't show it, there is a point where the compressed is so close to the original that you can't notice a difference. That is the key, to compress the data but still have a copy indistinguishable from the original. Because some data is discarded, lossy compression is only valid for audio or video. If you used lossy compression on text files, you would lose data. Examples of lossy compression are MP3's and jpeg's.

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