zeropad.m

介绍了傅立叶变换的基本原理

function [zi1,zi2] = zeropad(i1,i2,centre_flag) 
> USAGE: [zi1,zi2] = zeropad(i1,i2,centre_flag) 
> 
> function to zero-pad i1 and i2 so that they are exactly the same sizes 
> 
> centre_flag = 0 means pad from right and bottom edges 
> centre_flag = 1 means pad equally from ALL edges of the image 
> 
> A.I.Wilmer, Oct 2002 

> get the sizes of the images 
ht_i1 = size(i1,1); wd_i1 = size(i1,2); 
ht_i2 = size(i2,1); wd_i2 = size(i2,2); 

> zero-pad the height 
if (ht_i1 > ht_i2) > then zero-pad i2 
zi2 = zeros(ht_i1,wd_i2); 
if centre_flag 
start_ht = ceil((ht_i1-ht_i2)/2); 
zi2(start_ht:start_ht+ht_i2-1,:) = i2; 
else 
zi2(1:ht_i2,:) = i2; 
end 
zi1 = i1; 
elseif (ht_i2 > ht_i1) > zero-pad i1 
zi1 = zeros(ht_i2,wd_i1); 
if centre_flag 
start_ht = ceil((ht_i2-ht_i1)/2); 
zi1(start_ht:start_ht+ht_i1-1,:) = i1; 
else 
zi1(1:ht_i1,:) = i1; 
end 
zi2 = i2; 
else > then the images should have the same height 
zi1 = i1; 
zi2 = i2; 
end 

> zero-pad the width 
if (wd_i1 > wd_i2 ) > then zero-pad i2 
out2 = zeros(size(zi2,1),wd_i1); 
if centre_flag 
start_wd = ceil((wd_i1-wd_i2)/2); 
out2(:,start_wd:start_wd+wd_i2-1) = zi2; 
else 
out2(:,1:wd_i2) = zi2; 
end 
zi2 = out2; 
elseif (wd_i2 > wd_i1) > zeropad i1 
out1 = zeros(size(zi1,1),wd_i2); 
if centre_flag 
start_wd = ceil((wd_i2-wd_i1)/2); 
out1(:,start_wd:start_wd+wd_i1-1) = zi1; 
else 
out1(:,1:wd_i1) = zi1; 
end 
zi1 = out1; 
end > if images have the same width then the zi1 and zi2 images generated previously will not be altered...