Speckle Autocorrelation

Perform the Fourier transform based autocorrelation of grayscale frames to measure the speckle size. Also work with stacks of images

Takes frame (or stack of frames organized in x-y-FrameIndex) as input and performs the autocorrelation in x-y employng the Fourier ranform apporach. The resulting autocorrelation frame is averaged out for each input frame of the stack. After autocorrelation maxima is found, I compute the radial averaging. On the radial average of the AC, I perform Guassian fit to extract sigma and from that the FWHM. Togheter with this software I also provide a couple of speckles realizations (in staks or single frame in the files "Frm_Stack_Trial.mat", and "Frm_Trial.mat") . This routine also needs the radial average function radial_avg2.m (included).

[Frm_stack] : the input is a 3-d or 2-d matrix containing the speckles in the format x,y,,frame-index.

[FWHM] : Full width at half maximum of the speckle size (obtained with Gaussian fitting)

[AC XX] : Profile of the autocorrelation of the speckle frame; "plot(XX,AC)" to visaulize it

[curve] : result of the fit.to visaulize it "hold on; plot(curve)"

See also https://mlphotonics.wordpress.com/