How can I plot frequency vs magnitude of wavelet transform?

I am running Morlet continuous wavelet transform. I have got wscalogram of signal and now I want to plot freq-magnitude like the following picture., but I don't know how to do it:

I've used scal2freq MATLAB function to convert scales to pseudo frequencies. Also I have some frequencies in my signal that have a large damping ratio(4%) so they are not well visible in plot. How can I exaggerate these highly damped modes?

I am using MATLAB, here is my codes:

% Import the text4.txt to matlab workspace. and save it under name "data"
t=linspace(0,30,301);
Fs=ceil(inv(t(2)-t(1)));
x=data(:,4); % use x=data(:,3),x=data(:,5) too. first column is time,second is refrence
wname = 'morl';
scales = 1:1:256;
coefs = cwt(x,scales,wname,'lvlabs');
freq = scal2frq(scales,wname,1/Fs);
surf(t,freq,abs(coefs));shading('interp');
axis tight; xlabel('Seconds'); ylabel('Pseudo-Frequency (Hz)');

axis([0 30 0 1 0 60])
xlabel('Time'); ylabel('Frequency');
figure;
sc=wscalogram('image',coefs,'scales',freq,'ydata',x);
hold on 

My current plot looks like this:

Answer

Modifying your code a little bit, but no major changes, and I get correct results either way. Use this template code here, and you should not see any problems. I get the correct results.

clear all; 
t=linspace(0,30,301); 
Fs = (inv(t(2)-t(1))); 
x=randn(100,1);  
wname = 'morl'; 
scales = 1:1:256; 
chefs = cwt(x,scales,wname,'lvlabs');

freq = scal2frq(scales,wname,1/Fs);


figure; 
coefsSquared = abs(coefs).^2; 
imagesc(coefsSquared); 
grid off;

%Pick one of the columsn to plot: 
figure; 
plot(coefsSquared(:,47))

To get the figure on the right hand side of the first image you put up, that is simply the time-slice spectrum. In other words, one column of your frequency-time matrix.

For example, we might get the following squared-coefficient matrix, in frequency vs. time:

Let us then suppose we wish to look at the spectrum for the time-slice at column 47. Then, this is given here:

Here, you then see the power of the coefficients, vs. frequency, for the time-slice corresponding to column 47.