How to store a circle perimeter pixels in an array that is drawn over an binary image object?

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Zara Khan 2018-5-20

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评论： Zara Khan 2018-7-3

img1.png

I have drawn two circles over an binary image object by taking radius=half of the mean major and minor axis and another one is 0.7*radius. Also have drawn its minor axis. Now I want to consider the upper portion of the minor axis and want to store perimeter pixels of those semi circles in individuals array. How to do that ?

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Image Analyst 2018-7-1

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Image Analyst 2018-5-20

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Take your arrays that you drew, x and y, and extract only those above the center y value

indexes = y < centerY;  % Only those in the upper half.
xTop = x(indexes);
yTop = y(indexes);

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Image Analyst 2018-5-21

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You were not using the correct x for the circles. You were using the x of the elliptical fit of the hand. See this code:

a = imread('P1_G5_4.png');
c=imcomplement(a);
L=logical(c);
s=regionprops(L,'Centroid','MajorAxisLength','MinorAxisLength','Orientation')
circleCenterX =s.Centroid(1);
circleCenterY =s.Centroid(2);
diameters = mean([s.MajorAxisLength s.MinorAxisLength],2);
r =diameters/2;
r1=0.7*diameters;
subplot(1, 2, 1);
imshow(c);
hold on
t=0:0.1:2*pi;
%x_o and y_o = center of circle
x = circleCenterX + r * sin(t);
y = circleCenterY + r * cos(t);
plot(x,y,'r', 'LineWidth', 2);
t=0:0.1:2*pi;
x1 = circleCenterX + r1*sin(t);
y1 = circleCenterY + r1*cos(t);
plot(x1,y1,'m', 'LineWidth', 2);
axis('image', 'on');
t = linspace(0,2*pi,50);
a = s.MajorAxisLength/2;
b = s.MinorAxisLength/2;
% Xc = s.Centroid(1);
% Yc = s.Centroid(2);
% phi = deg2rad(-s.Orientation);
% x = Xc + a*cos(t)*cos(phi) - b*sin(t)*sin(phi);
% y = Yc + a*cos(t)*sin(phi) + b*sin(t)*cos(phi);
xMinor=s.Centroid(1)+[-2,2]*(s.MinorAxisLength/2)*sind(s.Orientation);
yMinor=s.Centroid(2)+[-0,0]*(s.MinorAxisLength/2)*cosd(s.Orientation);
line(xMinor, yMinor, 'LineWidth', 2);
plot(circleCenterX,circleCenterY,'r+', 'MarkerSize', 50, 'LineWidth', 2);
hold off
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0, 0.04, 1, 0.96]);
subplot(1, 2, 2);
imshow(c);
indexes = y < circleCenterY;  % Only those in the upper half.
xTop = x(indexes);
yTop = y(indexes);
axis square;
hold on;
plot(xTop, yTop, 'r-', 'LineWidth', 2);
indexes = y1 < circleCenterY;  % Only those in the upper half.
xTop1 = x1(indexes);
yTop1 = y1(indexes);
axis square;
hold on;
plot(xTop1, yTop1, 'm-', 'LineWidth', 2);
axis('image', 'on');
line(xMinor, yMinor, 'LineWidth', 2);
plot(circleCenterX,circleCenterY,'r+', 'MarkerSize', 50, 'LineWidth', 2);

Zara Khan 2018-7-2

Yes I have done that using 4 different variables then again have used some variables to draw 4 half circles then again taking 4 different loops for 4 different profiles ...this making the program lengthy and hard to handle ...how to do using loops ..can you please give me a some idea ?

Zara Khan 2018-7-3

Here indexes are always 1X63 for all the images. Hence the profiles are of 1X32 why? As there are two different half circle and there circumference lengths are also different still it is always coming 1X32 even for all the images in my folder this coming the same. Where is the problem in the above code?

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