Displaying area of each labeled region

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Syahrul Niezam 2012-2-8

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https://ww2.mathworks.cn/matlabcentral/answers/28493-displaying-area-of-each-labeled-region

评论： Image Analyst 2020-5-6

I would like to display area for each labeled region in the generated result image, after binarize and labeling gray-scale image. This is part of the codes:

hold on;
Measurements = regionprops(labImg, fgImg, 'all');   
numberOfBlobs = size(Measurements, 1);
for k = 1:numberOfBlobs 
  areas=Measurements(k).Area;
  plot(areas(:,2), areas(:,1), 2);
end
hold off;

Besides that, is there any idea to display labeled no. and area of labeled image in orders in command window?

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Walter Roberson 2012-2-8

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You should be able to use this outside of a loop:

blobareas = [Measurements.Area];
printf('%3d: %5d\n', [1 : length(blobareas); blobareas]);

Note: the Area field returned by regionprops() will always be a scalar, so accessing the second column of it like you do in areas(:,2) will cause an error.

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Walter Roberson 2012-2-9

If you only need the area shown on the screen, go back to the code in my Answer (except switching to fprintf and adding the Measurements assignment.)

Please explain further about how you would like to see the values represented as variables? With the code I posted earlier, the K'th blob's area is in blobarea(K)

Image Analyst 2012-2-9

He wanted to display the area "in the generated result image" so in that case he needs to get the centroid (via regionprops) and create a string with sprintf() and call text() to display it in the image at the location of the centroid, like I do in BlobsDemo. (I think I told him this already in one of his other related questions.)

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Image Analyst 2012-2-8

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https://ww2.mathworks.cn/matlabcentral/answers/28493-displaying-area-of-each-labeled-region#answer_36815

That looks strange. Why is areas a 2 element array, or a N by 2 array??? Anyway....

See my BlobsDemo http://www.mathworks.com/matlabcentral/fileexchange/25157 where I plot the label number at the centroid of the object. Basically you get the centroid and any other measurements you want then use sprintf() to create a string, then display that string with text() at the location of the centroid.

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MMSAAH 2020-5-6

在 MATLAB Online 中打开

Thank you for your reply and for sharing.

I ve changed the proposed code by :

blobMeasurements = regionprops(binaryImage, 'Centroid', 'Area', 'EquivDiameter');
% Get all centroids
allCentroids = vertcat(blobMeasurements.Centroid);
% Sort according to centroid's vertical location.
[sorted_y, sortOrder] = sort(allCentroids(:, 2), 'ascend');
% Reorder blobMeasurements
blobMeasurements = blobMeasurements(sortOrder);