Discrete Wavelet Transform (DWT)¶
Wavelet transform has recently become a very popular when it comes to analysis, de-noising and compression of signals and images. This section describes functions used to perform single- and multilevel Discrete Wavelet Transforms.
Single level dwt
¶
See the signal extension modes section for the list of
available options and the dwt_coeff_len()
function for information on
getting the expected result length.
The transform can be performed over one axis of multi-dimensional data. By default this is the last axis. For multi-dimensional transforms see the 2D transforms section.
Multilevel decomposition using wavedec
¶
Partial Discrete Wavelet Transform data decomposition downcoef
¶
Maximum decomposition level - dwt_max_level
, dwtn_max_level
¶
Result coefficients length - dwt_coeff_len
¶
Based on the given input data length (data_len
), wavelet decomposition
filter length (filter_len
) and signal extension mode, the
dwt_coeff_len()
function calculates the length of the resulting
coefficients arrays that would be created while performing dwt()
transform.
filter_len
can be either an int
or Wavelet
object for
convenience.