matlab 实现车牌的倾斜校正

clear,clc,close all;

%[fn,pn,fi]=uigetfile('*.jpg;*.bmp','选择图片');

I=imread('E:\picture\12.jpg');figure,imshow(I);title('原始图像');

bw=rgb2gray(I);

bw=im2bw(I,graythresh(bw));

bw=double(bw);

BW=edge(bw,'canny');

imshow(BW);title('canny 边界图像');

[H,T,R]=hough(BW);

figure,imshow(H,[],'XData',T,'YData',R,'InitialMagnification','fit');

xlabel('\theta'),ylabel('\rho');

axis on, axis normal,hold on;

P=houghpeaks(H,4,'threshold',ceil(0.3*max(H(:))));

x=T(P(:,2)); y = R(P(:,1));

plot(x,y,'s','color','white');

lines=houghlines(BW,T,R,P,'FillGap',50,'MinLength',7);

figure,imshow(BW),title('直线标识图像');

max_len = 0;

hold on;

for k=1:length(lines)

xy=[lines(k).point1;lines(k).point2];

% 标出线段

plot(xy(:,1),xy(:,2),'LineWidth',2,'Color','green');

% 标出线段的起始和终端点

plot(xy(1,1),xy(1,2),'x','LineWidth',2,'Color','yellow');

plot(xy(2,1),xy(2,2),'x','LineWidth',2,'Color','red');

len=norm(lines(k).point1-lines(k).point2);

Len(k)=len;

if (len>max_len)

max_len=len;

xy_long=xy;

end

end

% % 强调最长的部分

plot(xy_long(:,1),xy_long(:,2),'LineWidth',2,'Color','blue');

% [L1 Index1]=max(Len(:));

% % % 最长线段的起始和终止点

% x1=[lines(Index1).point1(1) lines(Index1).point2(1)];

% y1=[lines(Index1).point1(2) lines(Index1).point2(2)];

% % % % 求得线段的斜率

% K1=-(lines(Index1).point1(2)-lines(Index1).point2(2))/...

% (lines(Index1).point1(1)-lines(Index1).point2(1))

% angle=atan(K1)*180/pi

% A = imrotate(I,-angle,'bilinear');% imrate 是逆时针的所以取一个负号

% figure,imshow(A);

K1=-((xy_long(2,2)-xy_long(1,2))/(xy_long(2,1)-xy_long(1,1)))

%K1=-((xy_long(1,2)-xy_long(2,2))/(xy_long(1,1)-xy_long(2,1)))

angle=atan(K1)*180/pi

A = imrotate(I,-angle,'bilinear');% imrate 是逆时针的所以取一个负号

figure,imshow(A);