Data Compression - Systematisation
---- Data Reduction ----
by T.Strutz
Figure 5: 
Data Reduction comprises all methods, which reduce the irrelevant parts of the signal content resulting to changed signal information.
This requires preparatively a separation of relevant and irrelevant components
We can distinguish between quantisation, which decreases the resolution of the signal values, and sub-sampling decreasing the temporal or spatial resolution of signals.
If any part of a compression system applies a data-reduction method, the compression algorithms is called "lossy" due to the fact that data reduction changes the digital information. Contrary to this, in "lossless" compression schemes quantisation and sub-sampling are not allowed.
Strutz / 17.02.2003
