gusucode.com > 声音的处理有:LPC,FFT,共振峰,频谱源码程序 > siganlandsystemusingMatlab/SSUM/filters/image/d2dgauss.m
% Function "d2dgauss.m": % This function returns a 2D edge detector (first order derivative % of 2D Gaussian function) with size n1*n2; theta is the angle that % the detector rotated counter clockwise; and sigma1 and sigma2 are the % standard deviation of the Gaussian functions. function h = d2dgauss(n1,sigma1,n2,sigma2,theta) r=[cos(theta) -sin(theta); sin(theta) cos(theta)]; for i = 1 : n2 for j = 1 : n1 u = r * [j-(n1+1)/2 i-(n2+1)/2]'; h(i,j) = gauss(u(1),sigma1)*dgauss(u(2),sigma2); end end h = h / sqrt(sum(sum(abs(h).*abs(h)))); % Function "gauss.m": function y = gauss(x,std) y = exp(-x^2/(2*std^2)) / (std*sqrt(2*pi)); % Function "dgauss.m"(first order derivative of gauss function): function y = dgauss(x,std) y = -x * gauss(x,std) / std^2;