www.pudn.com > IrisLocate.rar > bandtrace.m

function [BD,BWT]=bandtrace(BW) 
%单次边界追踪 
%[BW,Lt]=im2bw_t(I,T); 
BD = [];%边界点坐标集合 
BWT = BW;%擦除已扫描的边界点后二值图像 
 
 
ST = fnd_stP(BWT); 
dir = [-1,-1]; 
%NextPoint(r,c)=[r,c]+dir 
%初始为左上方 
Point = ST; 
BD = [BD;ST]; 
NextP = Point + dir; 
while (NextP(1)*NextP(2)==0) | (NextP(1)>=size(BWT,1)) | (NextP(2)>=size(BWT,2)) 
    dir = dir_next(dir,0); 
    NextP = Point + dir; 
end 
BWT(Point(1),Point(2)) = 0;%擦除起始点 
%BWT(NextP(1),NextP(2)) 
%while 
totle = sum(sum(BWT)); 
i = 1;j = 0; 
while (i<=totle) & ((NextP(1)~=ST(1)) | (NextP(2)~=ST(2))) 
    if BWT(NextP(1),NextP(2)) == 0 
        if j >= 8 
            NextP = Point; 
            break; 
        end 
        j = j + 1; 
        dir = dir_next(dir,0); 
        NextP = Point + dir; 
    else 
        j = 0; 
        %标记为边界点 
        BD = [BD;NextP]; 
        BWT(NextP(1),NextP(2)) = 0;%擦除 
        Point = NextP; 
        dir = dir_next(dir,1); 
        NextP = Point + dir; 
        i = i + 1; 
    end 
    while (NextP(1)*NextP(2)==0) | (NextP(1)>=size(BWT,1)) | (NextP(2)>=size(BWT,2)) 
        dir = dir_next(dir,0); 
        NextP = Point + dir; 
    end 
end