How can I accurately plot the centroid of black dots in MATLAB?

Question

PamunkeBoy 2018-6-6

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/404420-how-can-i-accurately-plot-the-centroid-of-black-dots-in-matlab

评论： PamunkeBoy 2018-6-18

I have an Image in which I am trying to determine the centroid of the black dots. My Code seems to have trouble recognizing the centroid for all black dots as their respective shade of grey differs. Would anyone be able to guide me into how I could diagnose this? Thank you!

%%Centroid 
clear,clc
grid on
X = imread('redbox_5.bmp');
figure
imagesc(X)
se = strel('disk',3);
J = imsubtract(imadd(X,imtophat(X,se)),imbothat(X,se));
figure
imshow(J)
newmap2 = contrast(J,2);
colormap(newmap2)
figure(2);imshow(J);
%grey point less than 30
BW=J<30;
%Find Weighted Centroid of the chosen dots and plot them together with original image
%https://www.mathworks.com/matlabcentral/answers/332938-how-to-identify-black-dots-using-matlab
   rp=regionprops(BW,J,'WeightedCentroid');
        n=numel(rp);
           for j=1:n
               Position(j,1)=rp(j).WeightedCentroid(1);
               Position(j,2)=rp(j).WeightedCentroid(2);
           end
   for i=1:n-1
           if  (Position(i+1,1)-Position(i,1))<5 || (Position(i+1,2)-Position(i,2))<5
               Position(i+1,1)=1/2*(Position(i,1)+Position(i+1,1));
               Position(i+1,2)=1/2*(Position(i,2)+Position(i+1,2));
               Position(i,1)=0;Position(i,2)=0;
           end
           end
      [m,n]=size(Position);
      figure(3);imshow(J); axis image; hold on;
          for i=1:m
            for j=1:n-1
            plot(Position(i,j),Position(i,j+1),'r*')
            end
          end
       Position(all(Position==0,2),:)=[];
       display(Position);

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Answer 1

Anton Semechko 2018-6-7

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/404420-how-can-i-accurately-plot-the-centroid-of-black-dots-in-matlab#answer_323559

在 MATLAB Online 中打开

% Get the image
im=imread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/120388/MATLAB_QUESTION.PNG');
im=max(im,[],3);
% Segment blobs
bw=imclose(im<60,strel('disk',5));
% Cenroids of individual blobs
RP=regionprops(bw,'Centroid');
N=numel(RP);
C=zeros(N,2);
for i=1:N, C(i,:)=RP(i).Centroid; end
% Centroid of all blobs
C_net=regionprops(double(bw),'Centroid');
C_net=C_net.Centroid;
figure
imshow(bw)
hold on
plot(C(:,1),C(:,2),'or','MarkerSize',10,'LineWidth',2)
plot(C_net(:,1),C_net(:,2),'*g','MarkerSize',10,'LineWidth',2)