霍夫变换 ( Hough Transform） 直线检测(Matlab 源码)

关于霍夫变换直线检测的基本原理请参考下面

http://www.cnblogs.com/Ponys/p/3146753.html

Matlab代码如下：
clear
clc
close all;
%RGB = imread(‘circuit.tif’);
%RGB = imread(‘gantrycrane.png’);
RGB = imread(‘shizi.png’);
%RGB = imread(‘wanqu.png’);
I = rgb2gray(RGB);
BW = edge(I,’canny’);% Canny边缘检测 转换二值图像
figure
imshow(BW)
[H,theta,rho] = hough(BW,’RhoResolution’,0.5,’ThetaResolution’,0.5);
subplot(2,1,1);
imshow(RGB);
title(‘gantrycrane.png’);
subplot(2,1,2);
imshow(imadjust(mat2gray(H)),’XData’,theta,’YData’,rho,…
‘InitialMagnification’,’fit’);
title(‘Hough transform of gantrycrane.png’);
xlabel(‘\theta’), ylabel(‘\rho’);
axis on, axis normal, hold on;
colormap(hot);
P = houghpeaks(H,5,’threshold’,ceil(0.3*max(H(:))));
lines = houghlines(BW,theta,rho,P,’FillGap’,5,’MinLength’,7);
%% 画出图像中的直线
figure,
subplot(2,1,1);
imshow(BW), hold on
subplot(2,1,2)
imshow(BW)
hold on
max_len = 0;
for k = 1:length(lines)
xy = [lines(k).point1; lines(k).point2];
plot(xy(:,1),xy(:,2),’LineWidth’,2,’Color’,’green’);
% Plot beginnings and ends of lines
plot(xy(1,1),xy(1,2),’x’,’LineWidth’,2,’Color’,’yellow’);
plot(xy(2,1),xy(2,2),’x’,’LineWidth’,2,’Color’,’red’);
% Determine the endpoints of the longest line segment
len = norm(lines(k).point1 - lines(k).point2);
if ( len > max_len)
max_len = len;
xy_long = xy;
end
end

% highlight the longest line segment
plot(xy_long(:,1),xy_long(:,2),’LineWidth’,2,’Color’,’red’);