Westheimer line spread function
ls = westheimerLSF(xSec)
Spatial position is x in secs of arc of visual angle.
Westheimer calculated that the linespread function of the human
eye, specified in terms of minutes of arc and using a 3mm
pupil, should be approximated using the following formula
LineSpread = 0.47*exp(-3.3 *(x.^2)) + 0.53*exp(-0.93*abs(x));
Example:
vcNewGraphWin; xSec = -300:300;
plot(xSec,westheimerLSF(xSec)); grid on
xlabel('Position (arc sec)'); ylabel('Relative intensity');
xSec = -300:300; westheimerOTF = abs(fft(westheimerLSF(xSec)));
(One cycle spans 10 min of arc, or freq=1 is 6 cyc/deg)
freq = [0:11]*6;
vcNewGraphWin; plot(freq,westheimerOTF([1:12])); grid on;
xlabel('Freq (cpd)'); ylabel('Relative contrast');
set(gca,'ylim',[-.1 1.1])
Copyright ImagEval Consultants, LLC, 2005.