??? Undefined function or method 'fftshow' for input arguments of type 'double'.

Error ??? Undefined function or method 'fftshow' for input arguments of type 'double'.

when trying to display the image

 c=imread('cameraman.tif');
cf=fftshift(fft2(c));
 fftshow(cf,'abs') 
or fftshow(cf,'log');

both are showing the same error how to overcome this

Answer 1

[Wayne King]

What is fftshow.m ? That is not a MathWorks' function or method. If you have downloaded this MATLAB program from somewhere and saved it in a folder, then make sure you add that folder to the MATLAB search path with addpath or use pathtool.

Answer 2

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/41199-help-with-finding-a-function-should-be-a-simple-issue

[nethala bhanu]

sir pls show the code for iftt

[Steven Lord]

The code to call ifft is just ifft(). You need to fill in the input arguments to ifft inside those parentheses.

If you're asking to see the source code that implements ifft we do not distribute the source code for it. If you really want to see it start here.

[nethala bhanu]

is there any code for ifftshow .like fft show

Answer 3

[Kumar Vaibhav]

The error is due to fftshow function, which is not inbuilt function of MATLAB. You can find fftshow function in the link given below:

http://in.mathworks.com/matlabcentral/fileexchange/30947-gaussian-bandpass-filter-for-image-processing/content/fftshow.m

[Reham bun]

How can i inbuilt ifftshow? the fftshiw cannot be inverted why?

[nethala bhanu]

rehm bun did you get the code for iftt

Answer 4

[yanqi liu]

sir, may be use the follow code

clc; clear all; close all;
c=imread('cameraman.tif');
cf=fftshift(fft2(c));
figure;
fftshow(cf,'abs')
figure;
fftshow(cf,'log');

function fftshow(f,type)
% from:https://ww2.mathworks.cn/matlabcentral/fileexchange/30947-gaussian-bandpass-filter-for-image-processing
% Usage: FFTSHOW(F,TYPE)
%
% Displays the fft matrix F using imshow, where TYPE must be one of
% 'abs' or 'log'. If TYPE='abs', then then abs(f) is displayed; if
% TYPE='log' then log(1+abs(f)) is displayed. If TYPE is omitted, then
% 'log' is chosen as a default.
%
% Example:
% c=imread('cameraman.tif');
% cf=fftshift(fft2(c));
% fftshow(cf,'abs')
%
if nargin<2,
    type='log';
end
if (type=='log')
    fl = log(1+abs(f));
    fm = max(fl(:));
    imshow(im2uint8(fl/fm))
elseif (type=='abs')
    fa=abs(f);
    fm=max(fa(:));
    imshow(fa/fm)
else
    error('TYPE must be abs or log.');
end
end

you can read the book 《计算机视觉与深度学习实战》

[Reham bun]

Sorry, i want to implement Gaussian low pass filter for this image, I used this code (ifftshow) for the inverted fftshow but it didn't work with me because the file is not found.

Here's my code

a=imread('Fig0441(a).tif')
whos a 
g=fspecial('gaussian',688,10);
max(g(:));
g1=mat2gray(g);
max(g1(:));
f=fftshift(fft2(a));
i=f.*g1;
fftshow(i)
f1=ifft2(i);

[Reham bun]

Using

Answer 5

[yanqi liu]

sir, please copy to one m file, like follows

clc; clear all; close all;
a=imread('Fig0441(a).tif');
% whos a
g=fspecial('gaussian',688,10);
if ndims(a) > 2
    a = rgb2gray(a);
end
if ~isequal(size(a), size(g))
    a = imresize(a, size(g), 'bilinear');
end
max(g(:));
g1=mat2gray(g);
max(g1(:));
f=fftshift(fft2(a));
i=f.*g1;
fftshow(i)
f1=ifft2(i);
figure; imshow(f1, []);

function fftshow(f,type)
% from:https://ww2.mathworks.cn/matlabcentral/fileexchange/30947-gaussian-bandpass-filter-for-image-processing
% Usage: FFTSHOW(F,TYPE)
%
% Displays the fft matrix F using imshow, where TYPE must be one of
% 'abs' or 'log'. If TYPE='abs', then then abs(f) is displayed; if
% TYPE='log' then log(1+abs(f)) is displayed. If TYPE is omitted, then
% 'log' is chosen as a default.
%
% Example:
% c=imread('cameraman.tif');
% cf=fftshift(fft2(c));
% fftshow(cf,'abs')
%
if nargin<2,
    type='log';
end
if (type=='log')
    fl = log(1+abs(f));
    fm = max(fl(:));
    imshow(im2uint8(fl/fm))
elseif (type=='abs')
    fa=abs(f);
    fm=max(fa(:));
    imshow(fa/fm)
else
    error('TYPE must be abs or log.');
end
end

Answer 6

[Raghunathan P]

It is another library instead you can use this code:

c=imread('cameraman.tif');
cf=fftshift(fft2(c));

fl = log(1+abs(cf));  % Your DFT matrix of image 'cf' wil come HERE
fm = max(fl(:));
imshow(im2uint8(fl/fm))

or for advanced

function fftshow(f,type)
% Usage: FFTSHOW(F,TYPE)
%
% Displays the fft matrix F using imshow, where TYPE must be one of
% 'abs' or 'log'. If TYPE='abs', then then abs(f) is displayed; if
% TYPE='log' then log(1+abs(f)) is displayed. If TYPE is omitted, then
% 'log' is chosen as a default.
%
% Example:
% c=imread('cameraman.tif');
% cf=fftshift(fft2(c));
% fftshow(cf,'abs')

if nargin<2,
type='log';
end
if (type=='log')
fl = log(1+abs(f));  % Your matrix 'cf' wil come HERE instead of 'f'
fm = max(fl(:));
imshow(im2uint8(fl/fm))
elseif (type=='abs')
fa=abs(f);
fm=max(fa(:));
imshow(fa/fm)
else
error('TYPE must be abs or log.');
end;