How to implement sign operator using matlab

I was trying to implement a filter for digital image processing which require sign operator ie.

Can some tell me how to calulate it.

where ,X[u,v] is fast fourier transform of image.

[Walter Roberson]

https://www.mathworks.com/help/matlab/ref/sign.html

be sure to check that this is what you expect for complex inputs if that is a possibility

Answer 1

[Mathieu NOE]

hello

your code request the sign of the phase of fft2 output

example below - nothing fancy :

img   = imread('Noe_300dpi_3.jpg');
imagesc(img)
img   = fftshift(img(:,:,2));
F     = fft2(img);

figure;

imagesc(100*log(1+abs(fftshift(F)))); colormap(gray); 
title('magnitude spectrum');

figure;
imagesc(angle(F));  colormap(gray);
title('phase spectrum');

figure;
imagesc(sign(angle(F)));  colormap(gray);
title('phase spectrum sign');

you 'll notice the sharper output when you use sign(phase) instead of phase only

[Walter Roberson]

Is the phase of the fourier transform? The user indicated that is the fourier transform but did not define