How to detect the inner part of the core?

Hi,

I am trying to figure out how to find out the size of the core in the image, inner part for example best fit circle btu I am struggling, please see the code below I tried, and the images core is the main imafe and circle not fit is what I have tried so far. even if I can get some sort of contour of the inner core and extract the points and put the best fit circle but so far like 5 - 6 hours and no success here. Help would be great.

% Read in image

img = imread('Export.6t9zq5l4.000022a.jpg');

%[J,rect] = imcrop(img);

img = imcrop(img, [1030.51000000000,650.510000000000,638.980000000000,599.980000000000]);

% Convert image to grayscale

gray_img = rgb2gray(img);

% Smooth image

gray_img = medfilt2(gray_img, [3 3]);

% Apply threshold to grayscale image

threshold = graythresh(gray_img);

gray_img = imbinarize(gray_img, threshold);

gray_img = bwareaopen(gray_img, 1000);

figure(1)

imshow(gray_img)

se = strel('disk', 10);

dilated_img = imdilate(gray_img, se);

figure(2)

imshow(dilated_img)

eroded_img = imerode(dilated_img, se);

figure(3)

imshow(eroded_img)

[centers, radii] = imfindcircles(eroded_img, [40 55], 'ObjectPolarity','bright', 'Sensitivity',0.1);

viscircles(centers, radii, 'Color', 'r', 'LineWidth', 2);

figure(4)

imshow(eroded_img);

hold on;

viscircles(centers, radii, 'Color', 'r', 'LineWidth', 2);

hold off;

Answer 1

[Sulaymon Eshkabilov]

Have you seen the code proposed by Image Analyst: https://www.mathworks.com/matlabcentral/answers/245026-shape-detection-in-image

[muhammad choudhry]

Yea, the core is not basically well defined circle or ellipse hence what is in the link above not capturing accurately.