MATLAB中灰度图像的圆检测 [英] Circle detection from gray level image in MATLAB

问题描述

我的图像如下所示。我的目标是检测第二张图像中显示的圆圈。我使用 [centers，radii] = imfindcircles（IM，[100 300]）; 但它什么都没找到。

I have the image shown below. My aim is to detect the circle which shown in the second image. I used [centers,radii] = imfindcircles(IM,[100 300]); but it found nothing.

还有其他方法来检测圆圈吗？我怎么能这样做？

Is there any other way to detect the circle? How can I do that?

原始图片：

Original image:

圆圈：我用油漆画了它。

The circle:I drew it with paint.

推荐答案

这是imfindcircles的另一种解决方案。基本上对图像进行阈值处理，使用磁盘结构元素对其进行扩展，然后在找到边缘后，使用文件交换中可用的 circle_hough 算法应用Hough变换来检测圆圈此处。

Here is an alternative solution to imfindcircles. Basically threshold the image, dilate it with a disk structuring element and then, after finding the edges, apply a Hough transform to detect the circle using the circle_hough algorithm available form the file exchange here.

以下是代码：

clear
clc
close all

A = imread('CircleIm.jpg');

%// Some pre-processing. Treshold image and dilate it.
B = im2bw(A,.85);

se = strel('disk',2);

C = imdilate(B,se);

D = bwareaopen(C,10000);

%// Here imfill is not necessary but you might find it useful in other situations.
E = imfill(D,'holes');

%// Detect edges
F = edge(E);

%// circle_hough from the File Exchange.

%// This code is based on Andrey's answer here:
%https://dsp.stackexchange.com/questions/5930/find-circle-in-noisy-data.

%// Generate range of radii.
 radii = 200:10:250;

h = circle_hough(F, radii,'same');
[~,maxIndex] = max(h(:));
[i,j,k] = ind2sub(size(h), maxIndex);
radius = radii(k);
center.x = j;
center.y = i;

%// Generate circle to overlay
N = 200;

theta=linspace(0,2*pi,N);
rho=ones(1,N)*radius;

%Cartesian coordinates
[X,Y] = pol2cart(theta,rho); 

figure;

subplot(2,2,1)
imshow(B);
title('Thresholded image  (B)','FontSize',16)

subplot(2,2,2)
imshow(E);
title('Filled image (E)','FontSize',16)

subplot(2,2,3)
imshow(F);hold on

plot(center.x-X,center.y-Y,'r-','linewidth',2);

title('Edge image + circle (F)','FontSize',16)

subplot(2,2,4)
imshow(A);hold on
plot(center.x-X,center.y-Y,'r-','linewidth',2);
title('Original image + circle (A)','FontSize',16)

其中给出以下内容：

您可以使用传递给阈值的参数或扩大参数，看看它如何影响结果。

You can play around with the parameters passed to threshold or to dilate as well to see how it affects the outcome.

希望有所帮助！

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