GABIMAGEPARS Find Gabor parameters to generate image
Usage: [a,M,L,N,Ngood]=gabimagepars(Ls,x,y);
[a,M,L,N,Ngood]=GABIMAGEPARS(Ls,x,y) will compute a reasonable set of
parameters a, M and L to produce a nice Gabor 'image' of a signal
of length Ls. The approximate number of pixels in the time direction is
given as x and the number of pixels in the frequency direction is given
as y.
The output parameter Ngood contains the number of time steps (columns
in the coefficients matrix) that contains relevant information. The
columns from Ngood until N only contains information from a
zero-extension of the signal.
If you use this function to calculate a grid size for analysis of a
real-valued signal (using DGTREAL), please input twice of the desired
size y. This is because DGTREAL only returns half as many
coefficients in the frequency direction as DGT.
An example: We wish to compute a Gabor image of a real valued signal f*
of length 7500. The image should have an approximate resolution of
600 x800 pixels:
[f,fs]=linus; f=f(4001:4000+7500);
[a,M,L,N,Ngood] = gabimagepars(7500,800,2*600);
c = dgtreal(f,'gauss',a,M);
plotdgtreal(c,a,M,fs,90);
The size of c is (M/2)+1 xN equal to 601 x700 pixels.
For this function to work properly, the specified numbers for x and
y must not be large prime numbers.
Url: http://ltfat.github.io/doc/gabor/gabimagepars.html
See also: dgt, dgtreal, sgram.
Package: ltfat