MATLAB: How to draw a circle on specific points in an image??

image segmentation

plz helppppppp

Best Answer

If you just mean how to plot a circle in a figure, then this function will draw (an approximation to) a circle with a specified radius, at a specified (x,y) location. You can also specify the number of line segments that make up the circle.

function h = circle(x,y,r,nsegments)  
if nargin<4
    nsegments=50;
end
hold on
th = 0:2*pi/nsegments:2*pi;
xunit = r * cos(th) + x;
yunit = r * sin(th) + y;
h = plot(xunit, yunit);
hold off
end

I can't remember if I wrote this, or grabbed it off the File Exchange years ago, but there's no attribution in the file, so I can't give credit. You might search the FEX for other functions that may be better than this.

If you are talking more about image-processing, then I can't help you, except that I searched the FEX and found this:

http://www.mathworks.com/matlabcentral/fileexchange/23121-circle-on-image

Related Solutions

MATLAB: Drawing a segment of a circle

There are several files in the File Exchange that will do what you want. Here is one:

http://www.mathworks.com/matlabcentral/fileexchange/25580-ellipse

Also, here is a simple function that could be modified to draw just a segment:

function h = circle(x,y,r,nsegments)  
if nargin<4
    nsegments=50;
end
hold on
th = 0:2*pi/nsegments:2*pi;
xunit = r * cos(th) + x;
yunit = r * sin(th) + y;
h = plot(xunit, yunit);
hold off
end

MATLAB: I need help to plot circle around the points and these points are in a circle. please response

n=10; % number of points that you want
    center = [2 ,2]; % center coordinates of the circle [x0,y0] 

    radius = 10; % radius of the circle

      angle = 2*pi*rand(n,1);
      r = radius*sqrt(rand(n,1));
     X = r.*cos(angle)+ center(1);
     Y = r.*sin(angle)+ center(2);
     plot(X,Y,'.r')
     hold on
     %%Draw circle 
     R = 1. ;  % radius 
     th = linspace(0,2*pi) ;
     for i = 1:length(X)
         x = R*cos(th)+X(i) ;
         y = R*sin(th)+Y(i) ;
         plot(x,y,'b')
     end
     hold on
     center = [2 ,2]; % center coordinates of the circle [x0,y0] 
    radius = 10; % radius of the circle
    angle = 0:.01:2*pi;
    r = radius;
       X = r.*cos(angle)+ center(1);
       Y = r.*sin(angle)+ center(2);
     plot(X,Y,'.b')

Best Answer

Related Solutions

MATLAB: Drawing a segment of a circle

MATLAB: I need help to plot circle around the points and these points are in a circle. please response

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