noise removal without a built in function

I was wondering if there is any other way to remove the gaussian effect without using the built in wiener2 function for matlab ?

Answer 1

[Farouk Moukaddem]

Hi Jake,

There are several ways to remove noise from the 2-D data:

1) You can use the "medfilt2" function from the Image Processing Toolbox, which does 2-D median filtering.

>> B=medfilt2(A, [m n], padopt)

The command above performs median filtering of the matrix A in two dimensions. Each output element of the matrix B contains the median value in the m-by-n neighborhood around the corresponding element in the input matrix A.

For more information about the "medfilt2" function, refer to the documentation by executing the following at the MATLAB Command Line:

web([docroot '/toolbox/images/medfilt2.html'])

2) You can also use the "filter2" Matlab Function

>> Y=filter2(h,X,shape)

This command filters the data in X with the two-dimensional FIR filter in the matrix h. It computes the result, Y, using two-dimensional correlation, and returns the part of the correlation specified by the 'shape' parameter.

Refer to the documentation for more information by executing:

web([docroot '/techdoc/ref/filter2.html'])

Also refer to the following code that illustrates the above concepts:

% Set figure window size
dfpos = get(0,'DefaultFigurePosition');
figure('Position',dfpos([1 2 3 4]).*[1 1 1.5 1]);

% Smooth the noisy peaks data with MEDFILT2
ZN_smooth1=medfilt2(ZN, [15 15],'symmetric');
subplot(1,2,1);
surf(ZN_smooth1);
title('Peaks Surface (2-D median filter applied)')

% Smooth the noisy peaks data with FILTER2
h = fspecial('average', [10 10]);
ZN_smooth2=filter2(h,ZN,'valid');
subplot(1,2,2);
surf(ZN_smooth2);
title('Peaks Surface(2-D digital averaging filter applied)')

Thanks,

Farouk