function lpr_loc() 
% license plate recognition - car plate location based on color model
I=imread('Car2.jpg');
[y,x,z]=size(I);
myI=double(I);
%%%%%%%% Y 方向 %%%%%%%%%%
Blue_y=zeros(y,1)
for i=1:y
   for j=1:x
      if((myI(i,j,1)<=121)&&myI(i,j,1)>=110&&((myI(i,j,2)<=155)&&(myI(i,j,2)>=141))&&((myI(i,j,3)<=240)&&(myI(i,j,3)>=210))) % 藍色RGB的灰度范圍
       Blue_y(i,1)= Blue_y(i,1)+1;     % 藍色象素點統計   
       end  
   end
end
[temp MaxY]=max(Blue_y);        % Y方向車牌區域確定
PY1=MaxY;  %存放BLUE-Y列向量中的最大值，即整付圖象中行中符合IF 條件的灰度范圍的元素的最大個數
while ((Blue_y(PY1,1)>=5)&&(PY1>1))
    PY1=PY1-1;
end    
PY2=MaxY;
while ((Blue_y(PY2,1)>=5)&&(PY2<y))
      PY2=PY2+1;
end
IY=I(PY1:PY2,:,:);
%%%%%%%% X 方向 %%%%%%%%%% 
Blue_x=zeros(1,x);             % 進一步確定X方向的車牌區域
for j=1:x
  for i=PY1:PY2
      if((myI(i,j,1)<=121)&&myI(i,j,1)>=110&&((myI(i,j,2)<=155)&&(myI(i,j,2)>=141))&&((myI(i,j,3)<=240)&&(myI(i,j,3)>=210))) 
               Blue_x(1,j)= Blue_x(1,j)+1;     
           end  
    end       
end
PX1=1;
while ((Blue_x(1,PX1)<3)&&(PX1<x))%（采用的是排除法，行是選取法）
  PX1=PX1+1;%從前往后取符合(Blue_x(1,PX1)<3)條件的列，止到中間有一列斷開為止  
end   
PX2=x;
while ((Blue_x(1,PX2)<3)&&(PX2>PX1))
      PX2=PX2-1;%從后往前取符合(Blue_x(1,PX2)<3)條件的列，止到中間有一列斷開為止
end
IX=I(:,PX1:PX2,:);
PX1=PX1-2; % 對車牌區域的修正    
PX2=PX2+2;
IN=I(PY1:PY2,PX1:PX2-2,:)
Blue_y
figure,imshow(I);
figure,plot(Blue_y);
figure,plot(Blue_x);
figure,imshow(IX);
figure,imshow(IY);
figure,imshow(IN);