function?Y??=?downsample1（?X?rateidx）?
%?將圖像下采樣為原始圖像的1/rate的大小（長和寬都是原圖像的1/rate）
if?size（X?3）?==?3
????X?=?rgb2gray（X）;
end;

[row_Xcol_X]=size（X）;
m=fix（row_X./rate）;
ni?=?1;
Y?=?zeros（512512）;
nrate?=?floor（sqrt（rate））;
for?i=1:nrate:row_X
????nj?=?1;
????for?j=1:nrate:col_X
????????switch?idx
????????????case?1
????????????????Y（ninj）?=?X（ij）;
????????????case?2
????????????????Y（ninj）?=?X（i+1j）;
????????????case?3
????????????????Y（ninj）?=?X（ij+1）;
????????????case?4
????????????????Y（ninj）?=?X（i+1j+1）;
????????end
????????nj?=?nj+1;
????end?
????ni?=?ni+1;
end
Y=uint8（Y）;
%?Y=imresize（Y[row_Xcol_X]‘bicubic‘）;

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件?????236278??2013-05-10?14:57??compare.bmp

?????文件????????695??2013-12-08?22:26??downsample1.m

?????文件????????216??2013-12-08?22:25??gradient.m

?????文件?????263222??2013-05-08?21:23??lena.bmp

?????文件??????37521??2013-12-08?22:24??lena.jpg

?????文件?????521749??2013-12-08?22:23??lena.png

?????文件?????559146??2013-12-08?22:24??lena.tif

?????文件???????1549??2013-12-08?22:20??main.m

?????文件?????????74??2013-12-08?22:28??說明.txt

-----------?---------??----------?-----??----

??????????????1620450????????????????????9