Learn more about Signal Processing Blockset

DWT - Discrete wavelet transform (DWT) of input

Library

Transforms

dspxfrm3

Description

Note The DWT block is the same as the Dyadic Analysis Filter Bank block in the Multirate Filters library, but with different default settings. See the Dyadic Analysis Filter Bank block reference page for more information on how to use the block.

The DWT block computes the discrete wavelet transform (DWT) of each column of a frame-based input. By default, the output is a sample-based vector or matrix with the same dimensions as the input. Each column of the output is the DWT of the corresponding input column.

You must install the Wavelet Toolbox™ product for the block to design wavelet-based filters automatically to compute the DWT. Otherwise, you must specify your own lowpass and highpass FIR filters by setting the Filter parameter to User defined.

For the same input, the DWT block and the Wavelet Toolbox function do not produce the same results. Because the blockset is designed for real-time implementation and the toolbox is designed for analysis, the products handle boundary conditions and filter states differently. To make the output of the dwt function and the DWT block match, complete the following steps:

For the dwt function, set the boundary condition to zero-padding by typing dwtmode('zpd') at the MATLAB command prompt.
To match the latency of the DWT block, which is implemented using FIR filters, add zeros to the input of the dwt function. The number of zeros you add must be equal to the half the filter length.

For detailed information about how to use this block, see the Dyadic Analysis Filter Bank block reference page.

Examples

See Examples in the Dyadic Analysis Filter Bank block reference page.

DWT - Discrete wavelet transform (DWT) of input

Library

Description

Examples

See Also

Related Products & Applications

Dyadic Analysis Filter Bank	Signal Processing Blockset
IDWT	Signal Processing Blockset
`dwt`	Wavelet Toolbox