Definition: Computing routine or algorithm that reduces the size of a digital file but also loses information or data: generally this information is more or less redundant, and its loss allows for greater compression than with lossless routines. * Compression routines which give the highest compression ratios are lossy e.g. JPEG, MPEG.
Losing a free lunch or two
If you want the smallest possible file size -- say, for illustrating your web site so that people spend time looking at your site instead of picking their noses waiting for your images to download -- then you want lossy compression. JPEG can reduce file sizes to a twentieth of their size or less with not much loss in image quality. But other number-crunching methods, like wavelet maths, may allow improvements in compression ratios without compromise in image quality, but these are new formats and notoriously hard to have adopted.
Related Terms: JPEG
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