Draw a circle and measure the white pixels area inside

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Hello everyone, a binary image is obtained. The work is to draw concentric cirles in the image and calculate the area of the white pixels in each circle. The objective is to get a curve.
I attached an image as an example.
  2 Comments
Walter Roberson
Walter Roberson on 1 Aug 2019
Construct a binary mask which is a circle of appropriate radius at appropriate center. Use .* to multiply the mask and the binary form of the image. nnz() then gives the white count.
Hassan Khalil
Hassan Khalil on 1 Aug 2019
Thank you very much. It works. Not automatically for all the concentric radius but radius by radius. At each time, I change the radius value with the same center coordinates. The objective is done.

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Accepted Answer

Walter Roberson
Walter Roberson on 1 Aug 2019
You can construct a distance-squared matrix once. Then you can
sum(bsxfun(@le, distance_squared_matrix(:), radius_row_vector.^2))
to get the counts.

More Answers (1)

KSSV
KSSV on 1 Aug 2019
Edited: Walter Roberson on 1 Aug 2019
I = imread('image.png') ;
I1 = rgb2gray(I) ;
[y,x] = find(I1) ;
length(x)

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