There are different compression techniques that can be used for compressing plain text languages such as English, latin-based, Slovak and the like. Two examples are (1) RLE for Run length encoding and (2) LZ encoding to cover entropy encoding and Lamped-Ziv compression. While impressive compressions are available for video, as described in the next section, the best that can be expected for plain text is about 3:1.
Thus, a strong argument can be used for not bothering to compress alphanumerics at all, especially if there is embedded video such as graphics, sketches, drawings, and photos. For example, assume a report has 80 % plain text and 20% graphics.Read more at http://www.datadisc.com/