Autocorrelation and Self Convolution

» ell = fftprep(imread('ell.tif'),64);
» flops(0);
» ell_auto = auto(ell);
» flops

ans =  516998

» flops(0)
» ell_self = self(ell);
» flops

ans =  572742

Direct methods

Self convolution was done using conv2. The result was a 127 x 127 image.

» flops(0);
» self2 = conv2(ell,ell);
» self2 = self2/max(self2(:));
» flops

ans = 1097473

Auto-correlation was done using xcorr2 from the signal processing toolbox. The resulting image is also 127 x 127.

» flops(0);
» auto2 = xcorr2(ell,ell);
» auto2 = auto2/max(auto2(:));
» flops

ans = 1628277

Maintained by John Loomis, last updated 8 March 2000