Dilate a viscircles? circle fitting

Hello,

I have a binary imagen where I found 5 circles with imfindcircles and I plot them using viscircles. In order to do a least square fitting of that circle, I need to dilate this circles and get all edge pixels in a 2 pixel distance.

My problem is that I dont know how to dilate the circle that I get using viscircles, as this function only returns the center and radius of the circle. I know how to fit the circle, but, for that first I need to get those near pixels using a dilatation of the circle ploted by viscircles.

PD: Its a practice but our teacher told us to use dilatation to get those pixels and fit the circle.

This is my code

clc;clear;close all;

impath = 'metal-parts-01.png';
img = imread(impath);

%figure();
%imshow(img);

%figure();
%imhist(img);

%% filtro canny
F1= edge(img,'Canny',0.5,0.3);
figure();
imshowpair(img, F1, 'montage');
title(' Canny')
%% hough 
[A,theta,rho] = hough (F1);
%figure();
%imshow(imadjust(rescale(A)),'XData',theta,'YData',rho, 'InitialMagnification','fit')
%title(' transformada de hough')
%xlabel('\theta'), ylabel('\rho'); axis on, axis normal, hold on; colormap(gca,hot);
%% picos
peaks = houghpeaks(A,5,'Threshold',5);
%figure();
%imshow(A,[],'XData',theta,'YData',rho,'InitialMagnification','fit');
%title(' picos hough')
%xlabel('\theta'), ylabel('\rho'); axis on, axis normal, hold on; plot(theta(peaks(:,2)),rho(peaks(:,1)),'s','color','white');
%% lineas
lines = houghlines (F1,theta,rho,peaks);
figure()
imshow(img), hold on
max_len = 0;
for k = 1:length(lines) 
    xy = [lines(k).point1; lines(k).point2]; 
    plot(xy(:,1),xy(:,2),'LineWidth',2,'Color','green'); 
    plot(xy(1,1),xy(1,2),'x','LineWidth',2,'Color','yellow');   
    plot(xy(2,1),xy(2,2),'x','LineWidth',2,'Color','red');    
    % Determine the endpoints of the longest line segment    len = norm(lines(k).point1 - lines(k).point2);    if ( len > max_len)       max_len = len;       xy_long = xy;  
end
%% circulos
LowD = 6; LowL =25;
HighD =25; HighL = 80;
[centersL,radiiL]=imfindcircles(img,[LowL HighL],'ObjectPolarity','bright','Sensitivity',0.95);
[centersD,radiiD]=imfindcircles(img,[LowD HighD],'ObjectPolarity','dark','Sensitivity',0.90);
%figure()
%imshow(img), hold on
viscircles(centersD,radiiD);
viscircles(centersL,radiiL);

Answer 1

[mikel lasa]

Thank for the answer,

I solved the problem, I have created a zero matrix with my original edge image size and the input a circle with the command insert shape. Then I have converted to gray with rgb2gray.

After that, I made the dilate using this matrix.

Answer 2

[Manas Meena]

You can dilate objects from an image using imdilate.

• https://www.mathworks.com/help/images/ref/imdilate.html?searchHighlight=dilate%20objects&s_tid=srchtitle

Refer to the links below to learn about dilation of circles from an image

• https://www.mathworks.com/matlabcentral/answers/163732-dilate-objects-in-image?s_tid=answers_rc1-2_p2_MLT
• http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862