Data compression
From The Glossary of Digital Photography
A way of reducing the amount of storage space that any data, such as an image, takes. There are two types of data compression: lossless and lossy. In the lossy format, some data is thrown away to approximate the original with a much smaller file size. In lossless data compression, the original file can be reconstructed exactly. In some cases, a different format utilizing data compression techniques can be used for an image. Two examples of compressed data formats are JPEG and TIFF-LZW. JPEG is a lossy format; TIFF-LZW is a lossless format. JPEG images can be compressed a great deal. Generally, the more compression used in the format, the poorer the quality of the image. With TIFF-LZW, the compression is more modest and, in some cases, nonexistent. There are other techniques, such as ZIP, that can be used on images or groups of images. Data compression techniques such as ZIP are not as useful for images, aside from special image formats, as they are for other types of data. Besides the smaller storage requirements, another advantage to data compression is faster transmission to another computer or storage location. See also JPEG; TIFF, LZW; lossy; lossless
