MATLAB Matching Pursuit wmpdictionary using Gabor or customized atoms

Question

I am using MATLAB 2013, which now includes the Matching Pursuit algorithm. To create a dictionary has a function wmpdictionary . As far as I know, he is able to use the following functions to create atoms in a dictionary:

• Basis of Discrete Cosine Transformation-II
• Sine
• cosine
• polynomial
• Kronecker Delta Delta
• A valid orthogonal or biorthogonal wavelet family

I want / need to use Gabor .

Does anyone know how to use Gabor in wmpdictionary or, alternatively, a way to configure new kinds of atoms?

------------------ FINALLY SOLVED ------------------ I found the formula for Gabor atoms in [1]. I created a dictionary using the following functions:

function atom = getGaborAtom(N,scale,timeShift,frequency,phase) %This function obtains a Gabor atom of given parameters %N- Length of the signal %scale- must be in number of samples %timeShift - must be in number of samples %frequency - its normalized frequency from 0 to 0.5 f/fs; %Phase - a value from 0 to 2 pi %This version uses the number of samples but seconds can also be used. atom =zeros(N,1); for n=1:N atom(n,1) = (1/sqrt(scale))*exp(-pi*(n-timeShift)^2/scale^2) * cos(2*pi*frequency* (n-timeShift)+phase); end atom = (1/norm(atom)) .* atom; %Normalization end function [dictionary parameters]=constructDictionaryGabor() %Construct a Gabor dictionary %parameters are scale timeshift and frequency N=256; %Size of the atom scales = [2^1 2^2 2^3 2^4]; %More scales can be added freqs = [0 .001 .002 .05 .1 .2 .3 .4 .5]; % f/fs normalized frequency. More freqs can be added timeShifts = [0 64 128]; %More time shifts can be added phase =0; %More phase values can be added, here I'm fixinf phase to 0 dictionary = zeros(N,length(scales)*length(freqs)*length(timeShifts)*length(phase)); parameters = zeros(3,length(scales)*length(freqs)*length(timeShifts)*length(phase); contador = 1; for t=1:length(timeShifts) for f=1:length(freqs) for s=1:length(scales) dictionary(:,contador) = getGaborAtom(N,scales(s),timeShifts(t),freqs(f),phase); parameters(:,contador) = [scales(s) timeShifts(t) freqs(f)]; contador = contador+1; end end end end 

This dictionary can be used with the wmpdictionary function, the matrix parameters have parameters for each atom.

[1] Sound recognition of the environment using sound frequency characteristics

Answer 1

You must download and install MPTK, this toolkit has several functions and is faster than wmpalg. You can also create multi-channel decompositions and easily define your dictionaries.

Answer 2

You have to change this line

 atom(n,1) = (1/sqrt(scale))*exp(-pi*(n-timeShift)^2/scale^2) * cos(2*pi*frequency* (n-timeShift)+phase); 

For

 atom(n,1) = (1/sqrt(scale))*exp(-pi*(n-timeShift)^2/scale^2) * cos(2*pi*frequency* (n-timeShift)/N+phase);