Compressing Data

Throughout the articles included, you'll see references to methods of data compression or data encoding. Compression is the process used to reduce the physical size of a block of information. By compressing graphics data, we're able to fit more information in a physical storage space. Because graphics images usually require a very large amount of storage space, compression is an important consideration for graphics file formats. Almost every graphics file format uses some compression method.

There are several ways to look at compression. We can talk about differences between physical and logical compression, symmetric and asymmetric compression, and lossless and lossy compression. These terms are described in detail in Chapter 9, Data Compression. That chapter also describes the most common methods of, or algorithms for, compression, which we mention here briefly:

Each of the articles in Part Two, Graphics File Formats, lists the compression algorithms used for the particular graphics file format described.

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