function?C?=?contour_following（BW）
%?CONTOUR_FOLLOWING?takes?a?binary?array?and?returns?the?sorted?row?and
%?column?coordinates?of?contour?pixels.
%
%?C?=?CONTOUR_FOLLOWING（BW）?takes?BW?as?an?input.?BW?is?a?binary?array
%?containing?the?image?of?an?object?（‘1‘:?foreground?‘0‘:?background）.?It
%?returns?a?circular?list?（N?x?2?C（1:）=C（end:））?of?the?
%?（rowcolumn）-coordinates?of?the?object‘s?contour?in?the?order?of?
%?appearence?（This?function?was?inspired?from?the?freeman?contour?coding?
%?algorithm）.
%
%?Note:?
%?-?if?the?object?is?less?than?3?pixels?CONTOUR_FOLLOWING?sends?back?[0?0].
%?-?the?algorithm?is?quite?robust:?the?object?can?have?holes?and?can?also
%?be?only?one?pixel?thick?in?some?parts?（in?this?case?some?coordinates
%?pair?will?appear?two?times:?they?are?counted?“way?and?back“）.


[mn]=size（BW）;????????????????????????????????????????????????????????????%?getting?the?image?height?and?width

Itemp=zeros（m+2n+2）;??????????????????????????????????????????????????????%?we?create?a?‘0‘?frame?around?the?image?to?avoid?border?problems
Itemp（2:（m+1）2:（n+1））=BW;
BW=Itemp;

BW?=?BW?-?imerode（BW[0?1?0?;?1?1?1?;?0?1?0]）;?????????????????????????????%?gets?the?contour?by?substracting?the?erosion?to?the?image
BW?=?bwmorph（BW‘thin‘Inf）;???????????????????????????????????????????????%?to?be?sure?to?have?strictly?8-connected?contour

if?（sum（sum（BW））<3）???????????????????????????????????????????????????????%?we?consider?that?less?than?3?pixels?cannot?make?a?contour
????C=[0?0];?
????return;?
end;

[rowcol]=find（BW1）;??????????????????????????????????????????????????????%?takes?the?first?encountered?‘1‘?pixel?as?the?starting?point?of?the?contour

MAJ=[6?6?0?0?2?2?4?4];?????????????????????????????????????????????????????%?variable?initialization
C=[0?0?;?0?0];
k=0;
ended=0;
direction=4;

while（ended==0）
????k=k+1;
????found_next=0;??
????
????while（found_next==0）
????????switch?mod（direction8）
????????????case?0
????????????????if?（BW（row?col+1）==1）
????????????????????row=row;
????????????????????col=col+1;
????????????????????C（k:）=[row?col];
????????????????????found_next=1;
????????????????end;
????????????case?1;
????????????????if?（BW（row+1?col+1）==1）
????????????????????row=row+1;
????????????????????col=col+1;
????????????????????C（k:）=[row?col];
????????????????????found_next=1;
????????????????end;
????????????case?2;
????????????????if?（BW（row+1?col）==1）
????????????????????row=row+1;
????????????????????col=col;
????????????????????C（k:）=[row?col];
????????????????????found_next=1;
????????????????end;
????????????case?3;
????????????????if?（BW（row+1?col-1）==1）
????????????????????row=row+1;
????????????????????col=col-1;
????????????????????C（k:）=[row?col];
????????????????????found_next=1;
????????????????end;
????????????case?4;
????????????????if?（BW（row?col-1）==1）
????????????????????row=row;
????????????????????col=col-1;
????????????????????C（k:）=[row?col];
????????????????????found_next=1;
??????

?屬性????????????大小?????日期????時(shí)間???名稱
-----------?---------??----------?-----??----
?????文件????????4208??2007-05-21?11:51??contour_following.m
?????文件???????36054??2007-05-10?13:36??test1.bmp
?????文件???????36054??2007-05-10?13:37??test2.bmp
?????文件???????36054??2007-05-10?13:37??test3.bmp
?????文件???????36054??2007-05-10?13:37??test4.bmp
?????文件???????36054??2007-05-10?13:38??test5.bmp
?????文件????????1103??2007-05-10?13:39??Testscript.m