finding number of pixels inside each circle
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Dhandapani.S
le 21 Jan 2015
Commenté : Dhandapani.S
le 1 Fév 2015
i am drawing circles of different radius on a jpg image. how to find the number of pixels in each circle. i have to compare the pixel distribution ratio in each circle
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Image Analyst
le 26 Jan 2015
I'm pretty sure I gave you the answer in your other question: http://www.mathworks.com/matlabcentral/answers/169093#comment_261946 How is this any different than that?
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Image Analyst
le 26 Jan 2015
Just try it and see. Create a mask for triangles with poly2mask().
xTriangle = [x1,x2,x3,x1]; % Make a list of the coordinates of the vertices.
yTriangle = [y1,y2,y3,y1];
[rows, columns, numberOfColorChannels] = size(yourImage);
binaryImage = poly2mask(xTriangle, yTriangle, rows, columns);
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Thorsten
le 21 Jan 2015
A well-known "approximation" is :-)
N = round(radius^2*pi)
You could also create a circle and count the pixels:
radius = 100;
x = [-radius: radius];
[X, Y] = meshgrid(x, x);
R = sqrt(X.^2 + Y.^2);
N = numel(find(R<=radius));
Both values are almost the same.
2 commentaires
Thorsten
le 26 Jan 2015
You can just use any other value for the radius, like
radius = 50;
and then compute the N to count the pixels in the circle of radius 50. Or what else do you need?
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