Information Technology Reference
In-Depth Information
Horizontal spatial frequency
Low
High
8 pixels
8 pixels
Low
High
Fig. 13 Transform Basis Patterns of Two Dimensional 8x8 DCT
3.2.2.2 DWT
DWT is one of the transform methods using the transform basis made by the op-
eration of expanding and moving a function localized in frequency domain. DWT
allows using windows whose sizes are different according to frequencies, and has
the feature of high response for both low-frequency and high-frequency portions
of signals. DWT has also the following features,
(1)
The correspondence for local waveform change is high by using flexible
transform windows for unsteady signals
(2)
Block noise which is often present in DCT transform does not occur in-
side the window width for the conversion of lowest frequency
(3)
Hierarchical coding can be realized easily.
Search WWH ::




Custom Search