Hough transform for circles

A Hough transform function for detecting circles, optimised to allow search over radii.

Description

The Hough transform may be used to detect circular shapes in images, after binarisation, for example by an edge detector. Often, functions to do this operation require the radius of the circle to be specified.

The function circle_hough allows a range of radii to be specified, so that the radius does not need to be known exactly in advance. It is likely to be faster than calling a standard function repeatedly for different radii.

Multiple circles may be detected by finding peaks in the 3D accumulator array which is output. A function, circle_houghpeaks, is provided for this. A demonstration of the two function is included as a script, circle_houghdemo.

The zip file includes an efficient and accurate implementation of circle approximation, without gaps, on an integer grid.

Acknowledgements

Hough Transform For Circle Detection inspired this file.

This file inspired Automated Counting Of Bacterial Colonies and Wavelet Based Circular Hough Transform.

• Required Products: Image Processing Toolbox
• MATLAB release: MATLAB 7.10 (R2010a)

[David Young]

Hi narjes, The call to circle_hough has too many input arguments. Have a close look at it and compare it with the examples in the demo. If you need more help, please post the code that calls circle_hough.

[narjes]

hi David, when i use this code
some errors appear like :

?? Error using ==> nargchk
Too many input arguments.

Error in ==> C:\MATLAB6p5\work\circle_hough.m
On line 40 ==> error(nargchk(2, 2+length(opts), nargin, 'struct'));
could you help me please??

[David Young]

Hi Huanhuan. You need to download all the files in the submission and put them in a directory on your MATLAB path. It looks like you didn't download circlepoints.m.

[Huanhuan SHEN]

Hello, David
when I use this code, some problems come:

Undefined function 'circlepoints' for input arguments of type 'double'.

Error in circle_hough (line 61)
[tR, tC] = circlepoints(rrange(i));

Error in Circle_Detection2 (line 10)
h = circle_hough(e, radii, 'same', 'normalise');

Is that you have any idea about it?

[Andri Pranata]

thnx david :) i've actually created a code to detect some circle just like yours.. it ran perfectly, yours too.. but i still cant find a hough transform code to detect ellipse. ive search in file exchange, i found only one code. i try to run it, it works, but im not satisfied enough for the result :(

[David Young]

Hi Vijay. When you look at the image, how do you know which circles are particles and which are not? Can you turn that understanding into code to filter out the circles which you do not want?

[vijay mulchandani]

hello david,
i want to detect the circular glass particles in the images i get from PIV measuring technique. currently i am using hough transform, but it is showing circles which are not particles. could u help me

[David Young]

Hi Andri. That's not easy, and the solution depends on what your images look like - for example are the ellipses all very flattened, or are some of them close to being circles? If you have a general set of shapes, you probably need to use some kind of ellipse detector (not necessarily a Hough Transform) to find them. This will detect circles too, but you can then distinguish circles from ellipses simply on the basis of the aspect ration. I'm sorry, but my circle detector will probably not be very useful in the general case.

[Andri Pranata]

hey i'm andri form indonesia, i need some Hough Transform code that can see the difference between ellipse and circle.. could you help me with that? thank you :)

[joy barbosa]

 

[nourdine]

 

[nourdine]

...

[James]

Gracias David Young por este algoritmo, me ayudo mucho para detectar comprimidos en un blister,

[Fer]

 

[David Young]

Hi Ivan, thanks for the comment. If you set npeaks to 1, you will get the circle with the strongest evidence. If that is not the right circle, then you will need additional code to select the circle you want, using some other selection criteria, such as radius or position.

[Ivan]

wow, thanks a lot for the code David, helped with my project a lot!

just one question,

for example, if i were to set npeaks to 5, this will result in 5 circles being detected. however, i would only like one of the circle.

hence, is there a parameter i can set to eliminate the other circles? or do i have to add on to your code?

thank you so much!

[Nathan Orloff]

I tried several of the different Hough Circle detection algorithms. None of them were as easy to use or as robust as this one. It was also very fast in comparison to the editors pick of the week. Even the script circlepoints turns out to be faster than a standard trick in drawing a circle in matlab. My only suggestion is that you be a little nicer to the newbs David... :)

[Tristan]

Awesome Code David, Thanks Alot.
The patch you just mentioned for older versions of matlab worked perfect for me in R2007b

[Arefeh boroomand]

 

[David Young]

Hello TaoGe, I think you may be using an old version of Matlab that does not allow the use of ~ for anonymous variables. Please try replacing the ~ in line 113 of the file with a variable name, like this:

[unused, ind] = sort(h(peakind), 'descend');

[TaoGe ?]

Hello,May Good Job.
But to me,an error found:??? Error: File: circle_houghpeaks.m Line: 113 Column: 11
Expression or statement is incorrect--possibly unbalanced (, {, or [.

How to deal with it?
Thx~

[David Young]

Mash: Sorry, but I can't help. There could be many different reasons why this technique does not work for your project, and you may need to investigate other methods, as well as experimenting to find good parameter values for the edge detection and the HT itself. You might get more detailed advice by posting a request (with example images) on the newsgroup.

[Masih Soltany]

Hi

i want to use your code for my project on " eye detection "

i test but it had many miss place circle detection.

how can i optimize your code ?

thanks

[Steve Stefanou]

 

[Alireza Saberi]

 

[David Young]

Alireza Saberi: As this page shows, the code was built using Matlab 2010a. You should not give a low rating just because you have an old version of Matlab. You can delete calls to validateattributes (though you will lose error checking) and it may then run on your system.

On your second point: this isn't the place to discuss a specific application, and I suggest post the question on the newsgroup.

[Alireza Saberi]

Hello David,
It should be nice fast work. Here I have following Qs:
1- by running demo file on my LAB system i can see the following error
??? Undefined command/function 'validateattributes'.

Error in ==> circle_hough at 41
validateattributes(rrange, {'double'}, {'real' 'positive' 'vector'});

Error in ==> circle_houghdemo at 26
h = circle_hough(e, radii, 'same', 'normalise');

2- I have an algorithm for fatigue detection of a driver/pilot
the final steps, I have binarized image around pupil and even if the eye is open, i want and i need a good hough transform detect partials of circle of pupil, Can it do that or circle should be perfect for detection?

[Alireza Saberi]

 

[Truc Phan]

Great job! Thanks for sharing