How do you find a centroid of an image?
35 visualizaciones (últimos 30 días)
Mostrar comentarios más antiguos
Rish
el 5 de Ag. de 2014
Comentada: Image Analyst
el 25 de Oct. de 2017
I am trying to find the centroid of a binary image using region props but I keep receiving the error "Field reference for multiple structure elements that is followed by more reference blocks is an error". Here is my code for finding the centroid:
measurements = regionprops(bw, 'Centroid');
hold on;
plot(measurements.Centroid(1), measurements.Centroid(2), 'r+', 'MarkerSize', 120, 'LineWidth', 1);
hold off;
imshow(bw)
Any help would be appreciated thank you
1 comentario
Image Analyst
el 6 de Ag. de 2014
Do you want the centroid of the whole, entire image, or of individual blobs in the image? You asked about the whole image but your code seems to indicate you maybe want centroids of individual blobs. Of course the centroid of the whole image is at the center, and the "Weighted centroid" depends on the gray levels in the image.
Respuesta aceptada
Image Analyst
el 5 de Ag. de 2014
Maybe try
centroids = [measurements.Centroid];
xCentroids = centroids(1:2:end);
yCentroids = centroids(2:2:end);
plot(xCentroids, yCentroids, .............
2 comentarios
Image Analyst
el 6 de Ag. de 2014
Editada: Image Analyst
el 6 de Ag. de 2014
If you want the markers to be over the image, put "hold on" before plot(). You must have removed it for some reason.
hold on; % Prevent plot() from blowing away image.
plot(..........., 'r+'........
It looks like you used 'b-' in your call to plot because I see blue lines instead of red plus signs.
Más respuestas (6)
Nade Sritanyaratana
el 5 de Ag. de 2014
The example at the end of the regionprops documentation has an elegant use of the cat function, which might be able to fix the error you are getting.
measurements = regionprops(bw, 'Centroid');
imshow(bw);
centroids = cat(1,measurements.Centroid);
hold on;
plot(centroids(:,1), centroids(:,2), 'r+', 'MarkerSize', 120, 'LineWidth', 1);
hold off;
4 comentarios
Rujal
el 7 de Feb. de 2016
Editada: Rujal
el 7 de Feb. de 2016
I have used this code
but I want to find mid point between two centroids. for that I have used
mid= mean(centroids); plot(mid,'r*');
and the result is:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/182129/image.jpeg)
but I want to find midpoint between two centroids of objects. I would be thankful if someone helps me.
Image Analyst
el 7 de Feb. de 2016
You can't do that because centroids is [x1,y1,x2,y2,x3,y3,x4,y4,.....] You need to extract x and y separately:
xCenters = centroids(1:2:end);
yCenters = centroids(2:2:end);
Then you can pick out which two blobs you want to find the midpoint between and average them. For example
xMid = (xCenters(1)+xCenters(2))/2;
yMid = (yCenters(1)+yCenters(2))/2;
hold on;
plot(xMid, yMid, 'r+', 'LineWidth', 2, 'MarkerSize', 20);
hallouma amari
el 12 de Mayo de 2015
Editada: Image Analyst
el 12 de Mayo de 2015
help me too please
this is my error
Field reference for multiple structure elements that is followed by more reference blocks is an error.
img2=imread('56.png');
se=strel('disk',3);
J=imclose(img2,se);
J=rgb2gray(J);
M=imadjust(J);
B=0; %initialisation
[R C]=size(J);
measurements = regionprops(J, 'Centroid');
x2=measurements.Centroid(1);
y2=measurements.Centroid(2);
bw = bwboundaries(J);
boundary = bw{1};
x1=boundary(:,1);
y1=boundary(:,2);
x1 = x1-x2;
y1 = y1-y2;
1 comentario
Image Analyst
el 12 de Mayo de 2015
Try like what I showed:
centroids = [measurements.Centroid];
xCentroids = centroids(1:2:end);
yCentroids = centroids(2:2:end);
% Compute distances of perimeter to centroid of blob #1
bw = bwboundaries(J);
boundary = bw{1};
x1=boundary(:,1);
y1=boundary(:,2);
deltaXs = x1 - xCentroids(1);
deltaYs = y1 - yCentroids(1);
somia gupta
el 10 de Mayo de 2016
i want to find the centroid of an image in matlab ??? need help for the code for head pose detection
1 comentario
Image Analyst
el 10 de Mayo de 2016
See my Image Segmentation Tutorial in my File Exchange http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862 It goes over that plus more.
vinoba
el 11 de Mzo. de 2017
How to find centroid of each and every blob(objects) in a binary image?
1 comentario
Image Analyst
el 11 de Mzo. de 2017
See my Image Segmentation Tutorial in my File Exchange: http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862
Basically
[labledImage, numBlobs] = bwlabel(binaryImage);
props = regionprops(labeledImage, 'Centroid', 'WeightedCentroid');
You get a structure array with both types of centroids for every region.
tanuwyot
el 25 de Oct. de 2017
How to locate the nucleus centroid and extract the seven HU moments value ? Please help me
1 comentario
Image Analyst
el 25 de Oct. de 2017
Use regionprops(). See http://www.mathworks.com/matlabcentral/fileexchange/25157-image-segmentation-tutorial
I don't have code for Hu's moments.
Ver también
Productos
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!