How do I apply my filter to my image? (first matlab project)

First matlab project I've had so I'm not used to the system... ok so basically I'm trying to enhance an image I've done

>> Transformed = fft2(Image);
>> Shifted = fftshift(Transformed);
>> imshow(log(abs(Shifted)),[]);

Now I've used the fda tool to create a filter and I have saved this file

>> function Hd = filter1
%FILTER1 Returns a discrete-time filter object.

%
% MATLAB Code
% Generated by MATLAB(R) 7.12 and the Signal Processing Toolbox 6.15.
%
% Generated on: 11-Nov-2011 14:23:58
%

% Equiripple Lowpass filter designed using the FIRPM function.

% All frequency values are normalized to 1.

N     = 30;      % Order
Fpass = 0.2;     % Passband Frequency
Fstop = 0.8;     % Stopband Frequency
Wpass = 1;       % Passband Weight
Wstop = 1;       % Stopband Weight
dens  = 20;      % Density Factor

% Calculate the coefficients using the FIRPM function.
b  = firpm(N, [0 Fpass Fstop 1], [1 1 0 0], [Wpass Wstop], {dens});
Hd = dfilt.dffir(b);

% [EOF]

how do I apply this filter onto my image "Shifted" with mathlab syntax?

Thank you.

Answer 1

[Daniel Shub]

I would start by reading the documentation for dfilt

doc dfilt

From there you will see:

y = filter(Hd,x)

which in your case is really

Hd = filter1;
Filtered = filter(Hd, Image);

Answer 2

[Wayne King]

Since you're filtering an image, I would create a 2-D separable filter and use filter2. filter() will just apply a 1-D filter to the columns of your image. I think you want to filter both the columns and rows.

b  = firpm(N, [0 Fpass Fstop 1], [1 1 0 0], [Wpass Wstop], {dens});
b = b'*b;
outimage = filter2(b,imagedata);

Do you have the Image Processing Toolbox, if so, see the help for imfilter.