%?This?m-file?implements?the?mixture?of?Gaussians?algorithm?for?background
%?subtraction.??It?may?be?used?free?of?charge?for?any?purpose?（commercial
%?or?otherwise）?as?long?as?the?author?（Seth?Benton）?is?acknowledged.


clear?all

%?source?=?aviread（‘C:\Video\Source\traffic\san_fran_traffic_30sec_QVGA‘）;
source?=?aviread（‘..\test_video\san_fran_traffic_30sec_QVGA_Cinepak‘）;

%?-----------------------??frame?size?variables?-----------------------

fr?=?source（1）.cdata;???????????%?read?in?1st?frame?as?background?frame
fr_bw?=?rgb2gray（fr）;?????%?convert?background?to?greyscale
fr_size?=?size（fr）;?????????????
width?=?fr_size（2）;
height?=?fr_size（1）;
fg?=?zeros（height?width）;
bg_bw?=?zeros（height?width）;

%?---------------------?mog?variables?-----------------------------------

C?=?3;??????????????????????????????????%?number?of?gaussian?components?（typically?3-5）
M?=?3;??????????????????????????????????%?number?of?background?components
D?=?2.5;????????????????????????????????%?positive?deviation?threshold
alpha?=?0.01;???????????????????????????%?learning?rate?（between?0?and?1）?（from?paper?0.01）
thresh?=?0.25;??????????????????????????%?foreground?threshold?（0.25?or?0.75?in?paper）
sd_init?=?6;????????????????????????????%?initial?standard?deviation?（for?new?components）?var?=?36?in?paper
w?=?zeros（heightwidthC）;??????????????%?initialize?weights?array
mean?=?zeros（heightwidthC）;???????????%?pixel?means
sd?=?zeros（heightwidthC）;?????????????%?pixel?standard?deviations
u_diff?=?zeros（heightwidthC）;?????????%?difference?of?each?pixel?from?mean
p?=?alpha/（1/C）;????????????????????????%?initial?p?variable?（used?to?update?mean?and?sd）
rank?=?zeros（1C）;??????????????????????%?rank?of?components?（w/sd）


%?---------------------?initialize?component?means?and?weights?-----------

pixel_depth?=?8;????????????????????????%?8-bit?resolution
pixel_range?=?2^pixel_depth?-1;?????????%?pixel?range?（#?of?possible?values）

for?i=1:height
????for?j=1:width
????????for?k=1:C
????????????
????????????mean（ijk）?=?rand*pixel_range;?????%?means?random?（0-255）
????????????w（ijk）?=?1/C;?????????????????????%?weights?uniformly?dist
????????????sd（ijk）?=?sd_init;????????????????%?initialize?to?sd_init
????????????
????????end
????end
end

%---------------------?process?frames?-----------------------------------

for?n?=?1:length（source）

????fr?=?source（n）.cdata;???????%?read?in?frame
????fr_bw?=?rgb2gray（fr）;???????%?convert?frame?to?grayscale
????
????%?calculate?difference?of?pixel?values?from?mean
????for?m=1:C
????????u_diff（::m）?=?abs（double（fr_bw）?-?double（mean（::m）））;
????end
?????
????%?update?gaussian?components?for?each?pixel
????for?i=1:height
????????for?j=1:width
????????????
????????????match?=?0;
????????????for?k=1:C???????????????????????
????????????????if?（abs（u_diff（ijk））?<=?D*sd（ijk））???????%?pixel?matches?component
????????????????????
???????????????????

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????文件????????5224??2008-12-11?22:37??mixture_of_gaussians.m