How do you find a centroid of an image?
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Rish
am 5 Aug. 2014
Kommentiert: Image Analyst
am 25 Okt. 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 Kommentar
Image Analyst
am 6 Aug. 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.
Akzeptierte Antwort
Image Analyst
am 5 Aug. 2014
Maybe try
centroids = [measurements.Centroid];
xCentroids = centroids(1:2:end);
yCentroids = centroids(2:2:end);
plot(xCentroids, yCentroids, .............
2 Kommentare
Image Analyst
am 6 Aug. 2014
Bearbeitet: Image Analyst
am 6 Aug. 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.
Weitere Antworten (6)
Nade Sritanyaratana
am 5 Aug. 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 Kommentare
Rujal
am 7 Feb. 2016
Bearbeitet: Rujal
am 7 Feb. 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
am 7 Feb. 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
am 12 Mai 2015
Bearbeitet: Image Analyst
am 12 Mai 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 Kommentar
Image Analyst
am 12 Mai 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
am 10 Mai 2016
i want to find the centroid of an image in matlab ??? need help for the code for head pose detection
1 Kommentar
Image Analyst
am 10 Mai 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
am 11 Mär. 2017
How to find centroid of each and every blob(objects) in a binary image?
1 Kommentar
Image Analyst
am 11 Mär. 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
am 25 Okt. 2017
How to locate the nucleus centroid and extract the seven HU moments value ? Please help me
1 Kommentar
Image Analyst
am 25 Okt. 2017
Use regionprops(). See http://www.mathworks.com/matlabcentral/fileexchange/25157-image-segmentation-tutorial
I don't have code for Hu's moments.
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