I am plotting random circles using the plot function on a white background, how to convert this plot to a binary matrix?

Question

Mark Lepage 2019-2-1

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评论： Roger Pool 2019-2-2

采纳的回答： Mark Lepage

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So I am trying to simulate some random circles on an image.

I am creating a white background of the appropriate resolution by:

%Create blank white image
    xres = 2304;
    yres = 3456;
    
img = ones(xres,yres);
 
    %plot
    figure, imshow(img);
    hold on

Then generating a bunch of random circles using a custom function by:

%% Generate random bubble, based on above distribution         
        randomDiam = lognrnd(mu,sigma,nBubbles);
        randomX = yres*rand(nBubbles,1);
        randomY = xres*rand(nBubbles,1);
        
for ii = 1:nBubbles
    
generateCircle(randomX(ii),randomY(ii),randomDiam(ii));
 
end

My generateCircle function simply uses plot to plot the cricles:

function generateCircle(x,y,d)
 
%Resolution of circle set by 0.01 right now
theta = 0:0.01:2*pi;
 
%convert to circle plot
xp = (d/2)*cos(theta);
yp = (d/2)*sin(theta);
 
%plot
plot(x+xp,y+yp,'k');
 
end

This works great and creates the following:

However, I need to do further analysis on this. How do I convert this to an actual logical matrix?

The way I'm doing it now, the circles don't actually register in my img matrix.

Any ideas??

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Image Analyst 2019-2-2

shape_recognition_demo1.m

You can try my shape recognition code where I put up random shapes. Adapt the attached code as needed.

Roger Pool 2019-2-2

Thank you.

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Answer 1

Mark Lepage 2019-2-2

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https://ww2.mathworks.cn/matlabcentral/answers/442746-i-am-plotting-random-circles-using-the-plot-function-on-a-white-background-how-to-convert-this-plot#answer_359135

在 MATLAB Online 中打开

Hey everyone,

I got around this by using

imageOut = insertShape(img,'FilledCircle',M,'Color','black','Opacity',1);

where img is the white background I created, and M is an [x,y,r] matrix for the circles position and radii.

Thanks

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Answer 2

Image Analyst 2019-2-2

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https://ww2.mathworks.cn/matlabcentral/answers/442746-i-am-plotting-random-circles-using-the-plot-function-on-a-white-background-how-to-convert-this-plot#answer_359139

If you want solid circles, you can use poly2mask() to burn each circle into a binary image. Then OR that binary image from that one circle into your "master" image that contains ALL the circles.