Detect concentric empty rough circles

Question

Carine 2014-1-23

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113477-detect-concentric-empty-rough-circles

编辑： Carine 2014-3-27

Hello,

I want to be able to detect and draw a square around some circles. These circles are taken with a camera so depending of the angle of view and the distance, the radius vary and they can be deformed.Here are two examples: First example and Second example.

The last thing I have tried is using the CircularHough_Grd function from Tao Peng but it finds circles that are tangent of the sought circles: Result with CircularHough_Grd. And I am not sure how resistant this function is to deformation.

Any suggestion would be welcome as I am running a bit out of ideas at the moment.

Cheers.

2 个评论
显示无隐藏无

Image Analyst 2014-1-23

Can you attach them here using the image icon? My company policy has banned dropbox.

Carine 2014-1-23

编辑：Carine 2014-1-23

Above there is one and here is the second one

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Image Analyst 2014-1-23

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113477-detect-concentric-empty-rough-circles#answer_121964

Did you try imfindcircles()? http://www.mathworks.com/matlabcentral/fileexchange/34365-findcirclesgui

10 个评论
显示 8更早的评论隐藏 8更早的评论

Carine 2014-1-28

Hi again, I am of course spending the day on it... But the day is ending her in Europe. I have tried the another example but the result is rather worse. Your code give this plot:

</matlabcentral/answers/uploaded_files/7489/60b.jpg> and the boundary part:

More tomorrow.

I really appreciate your help! Cheers-

Carine 2014-1-30

在 MATLAB Online 中打开

Hello, I have finally something quite satisfying (history will see if fame is approaching dear Image Analyst ;-)):

    nomFile = 'Piscine80b.JPG';
   rgbImage = imread(nomFile);
    % Get the dimensions of the image.  numberOfColorBands should be = 3.
    [rows, columns, numberOfColorBands] = size(rgbImage);
    redChannel = rgbImage(:, :, 1);
    level = graythresh(rgbImage);
    binaryImage = im2bw(redChannel,level);
    binaryImage = bwareaopen(binaryImage, 20000);
    binaryImage = ~bwareaopen(~binaryImage, 20000);
    [labeledImage, numberOfBlobs] = bwlabel(binaryImage, 8);  
                % Label each blob so we can make measurements of it
    fprintf('Found %d blobs.\n', numberOfBlobs);
    coloredLabels = label2rgb (labeledImage, 'hsv', 'k', 'shuffle'); 
                                  % pseudo random color labels
    % Measure the regions
    measurements = regionprops(labeledImage, 'Perimeter', 'Area');
    % Select certain blobs based using the ismember function.
    % Let's say that we wanted to find only those blobs
    % with a circularity more than 5 or so.
    allBlobPerimeters = [measurements.Perimeter];
    allBlobAreas = [measurements.Area];
    allCircularities = allBlobPerimeters .^ 2 ./ (4*pi*allBlobAreas)
    % Get a list of the blobs that meet our criteria and we need to keep.
    % keeperIndexes = find(allCircularities < 1.5)
    [~,keeperIndexes] = min(allCircularities)
    % Extract only those blobs that meet our criteria, and
    % eliminate those blobs that don't meet our criteria.
    % Note how we use ismember() to do this.
    keeperBlobsImage = ismember(labeledImage, keeperIndexes);
    % Measure the regions, this time getting equivalent circular diameter and centroid.
    measurements = regionprops(logical(keeperBlobsImage), ...
      'Perimeter', 'Area', 'EquivDiameter', 'Centroid','BoundingBox');
    ecd = measurements.EquivDiameter
    equivDiameter(k,lettre) = ecd;
    c = measurements.Centroid;
    centroid(k,lettre,:) = c;
    BoundingBox = [measurements.BoundingBox]
    % Create a square mask including the circle
    x0 = BoundingBox(1); y0 = BoundingBox(2); % Upper left corner
    w = BoundingBox(3); h = BoundingBox(4); % Width and heigth
    dw = 0.1*w; dh = 0.1*h; % To let some margin
    mask = zeros(rows,columns); 
    mask(max(1,ceil(y0-dh)):min(rows,ceil(y0+h+dh)), ...
      max(1,ceil(x0-dw)):min(columns,ceil(x0+w+dw))) = 1;
    mask = logical(mask);
    Imask = rgbImage;
    Imask(~mask) = 255;
    IbinMask = ~(~binaryImage.*mask);
    close
    togglefig(nomFile)
    imshow(rgbImage)
    pause
    imshow(IbinMask)
    hold on
    plot(c(1), c(2), 'r+', 'MarkerSize', 20, 'LineWidth', 3);
    plot(c(1)-ceil(ecd/2):c(1)+ceil(ecd/2),c(2),'r','LineWidth', 3);
    hold off
     pause
 end
end

Using that, I can define the box around my "nearly circle" and select it, draw the equivalent diameter and the centre. Thank you again for you help!

请先登录，再进行评论。

Answer 2

Carine 2014-3-24

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113477-detect-concentric-empty-rough-circles#answer_130124

在 MATLAB Online 中打开

Hello,

I would like to reopen this question as, dealing with a noiser picture, it does not work anymore. For example, if I take a picture which I process and transform to black and white. I get this one:

Now, when I try to find regions with regionprops, it just finds one in red. Whereas I need the system to dectect my black circle.

</matlabcentral/answers/uploaded_files/10333/region.jpg> To get it, following the previous idea of this thread I do:

[labeledImage, numberOfBlobs] = bwlabel(binaryImage, 8);
coloredLabels = label2rgb (labeledImage, 'hsv', 'k', 'shuffle');
imshow(coloredLabels)

Any idea on how I could detect the circle?

Cheers.

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Image Analyst 2014-3-24

Fix your link, and post your original image.

请先登录，再进行评论。

Answer 3

Carine 2014-3-26

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/113477-detect-concentric-empty-rough-circles#answer_130517

编辑：Carine 2014-3-26

在 MATLAB Online 中打开

OK, here is a full example: I have this picture:

</matlabcentral/answers/uploaded_files/10400/Turbio10b.JPG> or link here. I process it using adapthisteq with Rayleigh distribution and clip of 1 and get:

</matlabcentral/answers/uploaded_files/10401/Turbio10bHistRay1.jpg> or link here: here or en formato fig.

Now I transform it to black and white and use bwareaopen to clean the image a bit:

</matlabcentral/answers/uploaded_files/10402/Turbio10bNB.jpg>, link here or here in fig.

Then if I try to find the blobs with

[labeledImage, numberOfBlobs] = bwlabel(binaryImage, 8);

I get this, link here or in fig . I find it very surprising as in very similar example, it works and detect both circles.

Cheers,

Carine.

P.S. I put hyperlink as it seems the direct links to the images don't work. I don't know why as when I download them, I am able visualize them but then it stop working.

3 个评论
显示 1更早的评论隐藏 1更早的评论

Carine 2014-3-27

No, if you can see my images, you will see that one of the circles is not detected. Yes I did use the image icon, choosing an image from my hard drive.