How to calculate amplitude of each frequency?
5 次查看(过去 30 天)
显示 更早的评论
I have an image and I have a code which gives the 2d fft of each color of the image. Now I need to calculate the amplitude of each frequency but I don’t know how to do it. Help is appreciated. Here’s my code so far:
im=imread('image ')/255.;
im1=im;
im=im(:,:,1);
imagefft2=fft2(im);
a=im_fft2;
a(angle(imagefft2)<pi/2)=1;
figure();
im1(:,:,1)=abs(ifft2(a));
imshow(im,[]);
0 个评论
采纳的回答
AdamG2013468
2019-8-21
For a 1-D fft, the process is as follows:
fs = %arbitrary sample frequency
N = length(signal);
fbins = [(0:1/N:1-1/N)*fs]; %frequency bin vector for plotting (x axis)
calval = N/2; %for two-sided ffts, calval should just be N for one-sided
[fftdat] = fft(signal);
fftmag = abs(fftdat)/calval;
%to visualize that expected magnitude is correct
figure
hold on
plot(fbins, fftmag)
See if you have any luck with a similar approach for your 2-D fft.
5 个评论
AdamG2013468
2019-8-21
编辑:AdamG2013468
2019-8-21
One way,
for i = 1:length(fftmag)
if fftmag(i) < 1/8
fftmag(i) = 0
end
end
更多回答(0 个)
另请参阅
类别
在 Help Center 和 File Exchange 中查找有关 Transforms 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!