Choosing the centroid of an specific shape

Question

Danny Guana 2023-2-7

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1908020-choosing-the-centroid-of-an-specific-shape

编辑： DGM 2023-2-7

I am trying to get the centre of a metallic cylinder ( see picture) using "regionprops" function. However, I get 100+ results. How can I choose the point closest to the centre? . Is there any way to focus on the metallic shape only ?

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Danny Guana 2023-2-7

Sure, this is my code:

I = imread('Test 3.jpg');

imshow(I)

A= rgb2gray (I)

imshow (A)

J = imadjust(A,stretchlim(A),[]);

imshow(J)

stat2 = regionprops(J,'centroid');

imshow(I); hold on;

for x = 1: numel(stat2)

plot(stat2(x).Centroid(1),stat2(x).Centroid(2),'ro');

end

Danny Guana 2023-2-7

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Answer 1

DGM 2023-2-7

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1908020-choosing-the-centroid-of-an-specific-shape#answer_1165575

编辑：DGM 2023-2-7

在 MATLAB Online 中打开

clean.png

Here. I tried to clean up the screenshot so that it's at least usable for a demo. Instead of using imadjust(), and trying to isolate the object by gray level alone, use the available color information to make the selection. You can try using the Color Thresholder App to get an idea of where to set the thresholds.

inpict = imread('clean.png');

% create simple mask in HSV

hsvpict = rgb2hsv(inpict);

mask = hsvpict(:,:,2)>0.375;

% clean up mask

mask = bwareafilt(mask,1); % select largest object

mask = bwconvhull(mask); % fill the blob by taking the convex hull

imshow(mask)

S = regionprops(mask,'centroid')

S = struct with fields:

Centroid: [711.5535 400.6236]

Note that the poor subject-background contrast and the uneven illumination are causing a lot of the problems here. If the script needs to handle many images, the variations are likely to require adjusting the thresholds unless you improve the physical setup.