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ridges

Extraction of ridges

Calling Sequence

[POINTST,POINTSF] = ridges(TFR, HAT)
[POINTST,POINTSF] = ridges(TFR, HAT, T)
[POINTST,POINTSF] = ridges(TFR, HAT, T, METHOD)
[POINTST,POINTSF] = ridges(TFR, HAT, T, METHOD, TRACE)
[POINTST,POINTSF] = ridges(...,'plot')

Parameters

TFR :

time-frequency representation

HAT :

complex matrix of the reassignment vectors.

T :

the time instant(s).

METHOD :

the chosen representation (default: 'tfrrsp').

TRACE :

A boolean (or a real scalar) if true (or nonzero),the progression of the algorithm is shown (default : %f).

'plot':

when called with the additional string 'plot', the output values will be plotted

POINTST:

a real vector: the time coordinates of the stationary points of the reassignment.

POINTSF:

a real vector: the frequency coordinates of the stationary points of the reassignment. Therefore, plot(POINTST,POINTSF,'.') shows the squeleton of the representation.

Description

ridges extracts the ridges of a time-frequency distribution. These ridges are some particular sets of curves deduced from the stationary points of their reassignment operators.

Examples

sig = fmlin(128,0.1,0.4);
g = window("kr",21,3*%pi)';
h = window("kr",47,3*%pi)';
t = 1:2:127;
[tfr,rtfr,hat] = tfrrspwv(sig,t,128,g,h);
[pt,pf] = ridges(tfr,hat,t,'tfrrspwv');
clf
Sgrayplot(t,linspace(0,0.5,128),tfr')
plot(pt,pf,".k")

See also

Authors


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