MATLAB: How to find the internal and external radius of a ring using matlab image processing toolbox

image processingmeasure internal diameter

For example get this image

Best Answer

By measuring the 'equivalent diameter' for each region, you can obtain the inner and outer radius. Here is an example.

% Read your image and binarize it
I = imread('Oil_Seal_Top_370003A__34285.1413827494.1280.1280.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')

The result is:

>> innerRadius
innerRadius =
278.8980
>> outerRadius
outerRadius =
374.5866

Related Solutions

MATLAB: 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

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')

MATLAB: How can i separate all the connected regions in a binary image and display them individually.

Use bwlabel() and ismember

[labeledImage, numRegions] = bwlabel(binaryImage);
props = regionprops(labeledImage, 'Area')
% Compute all the areas.
allAreas = [props.Area]
% Display each blob in its own figure.
for k = 1 : numRegions
    thisRegion = ismember(labeledImage, k);
    figure;
    imshow(thisRegion);
    drawnow;
end

Best Answer

Related Solutions

MATLAB: 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

MATLAB: How can i separate all the connected regions in a binary image and display them individually.

Related Question