Modulation Transfer Function

From: Pushker Pradhan (pushkar_at_erc.msstate.edu)
Date: 01/23/05 

Date: Sat, 22 Jan 2005 19:36:17 -0600

I want to calculate the Modulation Transfer Function at the Nyquist
Frequency. I'm using MATLAB so it already gives me the 2-D MTF (NxN matrix):
     PSF = fspecial('gaussian',13,1);
      OTF = psf2otf(PSF,[N N]); % PSF --> OTF (N can be any integer like
31, 512 etc.)
       % To visualize the OTF:
       subplot(1,2,1); surf(PSF); title('PSF');
       axis square; axis tight
       subplot(1,2,2); surf(abs(OTF)); title('corresponding |OTF|');
       axis square; axis tight

Can anyone tell me how I can evaluate or determine the MTF at the Nyquist
frequency, or a plot of the 1-D MTF?
Thanks, 

-- 
Pushkar Pradhan