x=[-25.132,-18.849,-12.566,-6.283,-3,0,3,6.283,12.566,18.849,25.132];
y=[0.21446,0.21446,0.21446,0.21446,44,44.15754,44,0.21446,0.21446,0.21446,0.21446];
LSF = [x,y] % This is more like a line spread function
OTF = fftshift(fft(LSF)); % OTF
MTF = abs(OTF); % absolute value of OTF
MTF = MTF./max(MTF); % normalize
% correct sampling frequency for conversion on frequency bins to frequency
Size = length(MTF);
spacing = 3;% spacing between data points
fsx = abs(1/spacing); % turn into sampling frequency
a = linspace(-Size/2,Size/2,Size); % form scale for conversion based on frequency bins
conversionx = fsx./Size; % conversion factor for frequency bin units to frequency (unit^-1)
Psi = a.*conversionx; % frequency (unit^-1)
plot(Psi,MTF)
xlim([0,Psi(end)])
xlabel('cycles/unit')
ylabel('MTF')
