crosspowerspectrum.m

介绍了傅立叶变换的基本原理

function cps = crosspowerspectrum(in1,in2) 
> USAGE : cps = crosspowerspectrum(in1,in2) 
> 
> function to calculate the PHASE-CORRELATION, hence function name may be a bit misleading!! 
> 
> Adam Wilmer, 3-9-02 

F1 = fft2(in1); 
F2 = fft2(in2); 

> Create phase difference matrix 
pdm = exp(i*(angle(F1)-angle(F2))); 

> turn into cross phase-correlation 
cps = real(ifft2(pdm)); 

> had problems with NaN's coming out so check this 
if(mean(mean(isnan(cps)))>0.95) 
disp('PROBLEM ALERT: phasecorrelation contains a lot of NaNs (check FFTs exist as they cannot cope with certain inputs for some reason)') 
return 
end