matlab圆的检测,Hough圆检测的matlab实现 | 学步园

源代码：

m文件1：

function newPic=hough_circle_main(oldPic)

close all

clear

clc

[filename,pathname]=uigetfile({'*.bmp;*.jpg;*.tif;*.gif'},'newpic');

if isequal(filename,0)

disp('User selected cancel')

else

disp(['User selected: ',fullfile(pathname,filename)])

end

root=fullfile(pathname,filename);

oldPic=imread(root);

I=oldPic;

% close all

% clear

% clc

%

% I=imread('circle.bmp');

[m,n,k] = size(I);

if k>1

I = rgb2gray(I);

end

BW = edge(I,'sobel');

step_r = 10;

step_angle = 0.1;% 5.7296 degrees

minr = 100;      %need to modify by fact

maxr = 200;      %need to modify by fact

thresh = 0.5;    % 76.8000

[hough_space,hough_circle,para] = hough_Circle(BW,step_r,step_angle,minr,maxr,thresh);

subplot(221),imshow(I),title('原图')

subplot(222),imshow(BW),title('边缘')

subplot(223),imshow(hough_circle),title('检测结果')

M文件2：

function [hough_space,hough_circle,para] = hough_Circle(BW,step_r,step_angle,r_min,r_max,p)

% %%%%%%%%%%%%%%%%%%%%%%%%%%

% input

% BW:二值图像；

% step_r:检测的圆半径步长

% step_angle:角度步长，单位为弧度

% r_min:最小圆半径

% r_max:最大圆半径

% p:以p*hough_space的最大值为阈值，p取0，1之间的数

% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% output

% hough_space:参数空间，h(a,b,r)表示圆心在(a,b)半径为r的圆上的点数

% hough_circl:二值图像，检测到的圆

% para:检测到的圆的圆心、半径

[m,n] = size(BW);

size_r = round((r_max-r_min)/step_r)+1;

size_angle = round(2*pi/step_angle);

hough_space = zeros(m,n,size_r);

[rows,cols] = find(BW);

ecount = size(rows);

% Hough变换

% 将图像空间(x,y)对应到参数空间(a,b,r)

% a = x-r*cos(angle)

% b = y-r*sin(angle)

for i=1:ecount

for r=1:size_r

for k=1:size_angle

a = round(rows(i)-(r_min+(r-1)*step_r)*cos(k*step_angle));

b = round(cols(i)-(r_min+(r-1)*step_r)*sin(k*step_angle));

if(a>0&a<=m&b>0&b<=n)

hough_space(a,b,r) = hough_space(a,b,r)+1;

end

end

end

end

% 搜索超过阈值的聚集点

max_para = max(max(max(hough_space)));

index = find(hough_space>=max_para*p);

length = size(index);

hough_circle=zeros(m,n);

for i=1:ecount

for k=1:length

par3 = floor(index(k)/(m*n))+1;

par2 = floor((index(k)-(par3-1)*(m*n))/m)+1;

par1 = index(k)-(par3-1)*(m*n)-(par2-1)*m;

if((rows(i)-par1)^2+(cols(i)-par2)^2

(rows(i)-par1)^2+(cols(i)-par2)^2>(r_min+(par3-1)*step_r)^2-5)

hough_circle(rows(i),cols(i)) = 1;

end

end

end

% 打印结果

for k=1:length

par3 = floor(index(k)/(m*n))+1;

par2 = floor((index(k)-(par3-1)*(m*n))/m)+1;

par1 = index(k)-(par3-1)*(m*n)-(par2-1)*m;

par3 = r_min+(par3-1)*step_r;

fprintf(1,'k=%d Center (%d,%d) radius %d\n',k,par2,par1,par3);

para(:,k) = [par1,par2,par3];

end

end