I tried to find inner and outer diameter of an circle using this code but it didn't give me outputs images like below I've attached

Here is the code % Read your image and binarize it I = imread('C:\Users\Rangika Mark\Desktop\WP_20171207_11_47_46_Selfie.jpg'); Igray = rgb2gray(I); BW = imbinarize(Igray); % Measure the outer radius BWout = ~BW; BWout = imfill(BWout,'holes'); statOuter = regionprops(BWout,{'EquivDiameter','Centroid'}); outerRadius = statOuter.EquivDiameter/2; % Measure the inner radius BWin = imclearborder(BW); BWin = imopen(BWin, strel('disk',5)); % Remove noise statInner = regionprops(BWin,{'EquivDiameter','Centroid'}) innerRadius = statInner.EquivDiameter/2; % Show the result figure imshow(I) hold on viscircles(statOuter.Centroid, outerRadius,'Color','r') viscircles(statInner.Centroid, innerRadius,'Color','r')

Answer 1

[Akira Agata]

In this case, you should pick up the region, that has maximum diameter, from the output of regionprops function. Based on your original code, I have slightly modified to do that.

I = imread('8122bCXHqPL._SY463_.jpg');
Igray = rgb2gray(I);
BW = imbinarize(Igray); 
% Measure the outer radius 
BWout = ~BW; 
BWout = imfill(BWout,'holes');
statOuter = struct2table(regionprops(BWout,{'MajorAxisLength','Centroid'}));
[~,idxOuter] = max(statOuter.MajorAxisLength);
outerRadius = statOuter.MajorAxisLength(idxOuter)/2; 
% Measure the inner radius 
BWin = imclearborder(BW); 
BWin = imopen(BWin, strel('disk',5)); 
statInner = struct2table(regionprops(BWin,{'MajorAxisLength','Centroid'}));
[~,idxInner] = max(statInner.MajorAxisLength);
innerRadius = statInner.MajorAxisLength(idxInner)/2; 
% Show the result 
figure
imshow(I) 
hold on 
viscircles(statOuter.Centroid(idxOuter,:), outerRadius,'Color','r') 
viscircles(statInner.Centroid(idxInner,:), innerRadius,'Color','r')

[Rangika Mark]

Thank you Mr. Akira Agata,It was success thank you for your assistance