This abstract class represents a subband in a bidirectional tree structure that describes the subband decomposition for a wavelet transform. This class is implemented by the SubbandAn and SubbandSyn classes, which are for the analysis and synthesis sides respectively.

The element can be either a node or a leaf of the tree. If it is a node, it has 4 descendants (LL, HL, LH and HH). If it is a leaf, it has no descendant.

The tree is bidirectional. Each element in the tree structure has a "parent", which is the subband from which the element was obtained by decomposition. The only exception is the root element which, for obvious reasons, has no parent (i.e. it is null).

'Declaration
 
Public MustInherit Class Subband 

public abstract class Subband