www.gusucode.com > 超声波测量以及形成图像 对相关信号进行模拟仿真 > 超声波测量以及形成图像 对相关信号进行模拟仿真/digital holograpy/prog/variance.m
function [ b ] = variance( a,sz ) %VARIANCE 2-D variance distribution of an array % For each element of a 2-D array a, a variance % value is calculated and stored in the same element % in b. This varience value is varience of the data % in a window whose center is that element being % considered. sz is the size of the window error(nargchk(2,2,nargin)) if nargout>1 error('Too many output arguments') end [M,N]=size(a); b=zeros([M,N]); av=conv2(a,ones(sz(1),sz(2)),'same')./sz(1)./sz(2); left=round((sz(2)-1)/2); right=sz(2)-1-left; up=round((sz(1)-1)/2); down=sz(1)-1-up; for svy=up:-1:-down for svx=left:-1:-right b=b+abs(av-circshift(a,[svy,svx])).^2; end end