A single stream can be compressed and encoded using multiple
methods. This property reflects the primary compression type used
by the stream.
Compression types which result in high levels of compression
(e.g. JPEG) are considered more important than those that do not
(e.g. ASCII 85).
The CompressionType enumeration may take the following
More details of these compression types can be found in Section
3.3 of the Adobe PDF Specification.