MATLAB: Wavelet Packet Decomposition filter specification

wavelet packet decompositionWavelet Toolboxwavelets

Hi, I am looking to perform Wavelet Packet Decomposition on a 2 dimensional image using my own filter coefficients.
I have noticed that when performing standard 2-D Wavelet Decomposition there is a function 'dwt2' which takes high and low pass filters as parameters, however when performing Wavelet Packet Decomposition only a wavelet name can be specified and not the actual filters.
Just wondering is anyone aware of a function which will enable me to specify my own high and low pass filters for use with Wavelet Packet Decomposition? Or, if anyone has any ideas these would also be greatly appreciated.
thanks, John

Best Answer

Hi John, yes the filter I gave you above matches exactly. What you have to realize is that Wavelet Toolbox multiplies the orthogonal lowpass filter by sqrt(2) so that it satisfies the properties of a conjugate quadrature filter. This is built into the way Daubechies describes her filters. She describes them divided by sqrt(2).
If you do this:
[LoD,HiD] = wfilters('db10');
h = fliplr(LoD/sqrt(2))
You will see exactly the filter you are looking for. So you can just use wpdec2() with 'db10'.
Hope that helps
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