denoising using wavelet

How i can do denoising of 2-D signals with wavelet by using matlab cods ? plz help me :(

Answer 1

[Wayne King]

I'm not sure why your original post was about 2-D and it turns out that you have 1-D signals.

Yes, what you have done is basically correct. You could also use wden().

[hajer]

plz how i can differentiation between 1-D and 2-D

also , if i have signal extracted from ECG device and it mix from mother and fetus signal

is it 1-D or 2-D ???????

Sorry for the inconvenience

[Wayne King]

Hi, 2-D is an image, a function of two variables. ECG is 1-D signal. It is a function of one variable (time -- even though it is sampled).

If you have two ECG signals, you have two 1-D signals.

Answer 2

[Wayne King]

Hi, You have a couple of options.

1.) use wavemenu. Enter wavemenu at the command line and then choose, Wavelet 2-D, or SWT Denoising 2-D. Starting in R2011b, you can generate MATLAB code for your denoising directly from the wavemenu GUI.

From the command line, you can use wavedec2 and wdencmp, for decimated 2-D Wavelet denoising, and swt2 and wthresh or stationary wavelet 2-D denoising.

There are some good User's Guide examples of using the GUI and generating MATLAB code for 2-D denoising here:

http://www.mathworks.com/help/toolbox/wavelet/ug/bs3fc_j.html

and here:

http://www.mathworks.com/help/toolbox/wavelet/ug/bs34y5l.html

Note that the generated code in these examples also shows you how to implement 2-D wavelet denoising from the command line.

[hajer]

thanks very much Wayne King ....

if i have two mixed ecg signals

and i added some noise to signals

then i called ddencmp and wdencmp functions

like this

% load 2 ecg signals

x1 = repmat(ecg(50), 1, 8);

x2 = repmat(ecg(25), 1, 16);

%plotting commands

figure (1),

subplot(2,1,1),plot(x1)

title(strcat(['Original signals' ]));

subplot(2,1,2),plot(x2)

%mixed signal

s=[x1;x2];

A=randn(10,2);

mixed = A*s;

%Noise

noise = randn(10,length(mixed)).*0.18;

signalWithNoise=mixed+noise;

%----------------denoising------------%

[thr,sorh,keepapp] = ddencmp('den','wv',signalWithNoise);

xd =wdencmp('gbl',signalWithNoise,'sym10',10,thr,sorh,keepapp);

is denoising right or not ??

Answer 3

[shivangi b]

sir,

for image de-noising using stationary wavelet transform and threshold techiques I have used

THR = wthrmngr('sw1ddenoLVL',METHOD,SWTDEC,SCAL)

command swtdec =db1,scal= 2 ,method ='rigsure'.

couldn't decompose the original image and hard and soft threshold used . plz replay me sir id:[e-mail]

[Geoff Hayes]

As this isn't an answer to the posted question, please delete and post as your own question.