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Time Frequency Toolbox >> Time Frequency Toolbox > Linear Time-Frequency Processing > tfrsurf

tfrsurf

extract from a time-frequency representation the biggest energy dots

Calling Sequence

[tfr2,OrderedSurfaces]=tfrsurf(tfr);
[tfr2,OrderedSurfaces]=tfrsurf(tfr,threshold);
[tfr2,OrderedSurfaces]=tfrsurf(tfr,threshold,keep);
[tfr2,OrderedSurfaces]=tfrsurf(tfr,threshold,keep,trace);

Parameters

TFR :

time-frequency representation.

THRESHOLD :

the energy threshold, in %

KEEP :

number of dots to keep

TRACE :

if nonzero, the progression of the algorithm is shown (default : 0).

Examples

N=256;
sig=fmlin(N,0.1,0.3)+fmlin(N,0.3,0.4)+2*fmlin(N,0.05,0.2).*amgauss(N,190,70);
tfr=tfrwv(sig,1:N,128);
[tfr2,OrderedSurfaces]=tfrsurf(tfr,5,3,1);
scf(1);tfrview(tfr,sig,1:N,'tfrwv',[2 1 5 10 128 2 1 0 0 .5])
title('original tfr');
scf(2);tfrview(tfr2,sig,1:N,'tfrwv',[2 1 5 10 128 2 1 0 0 .5]);
title('modified tfr');
scf(3);plot(1:10,OrderedSurfaces(1:10),'-',1:10,OrderedSurfaces(1:10),'o'); //semilogy
title('number of points of the 10 biggest dots');
    See also
imextract.

Authors

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