How can calculate the average diamter of below image using matlab?

Hello,

I'd like to calculate the average diamtere of below microstructure using matlab.

Is it possible to calculate it or not?

The actual size of below image is 256um*256um.

Answer 1

[Jeff E]

I'd start by looking at the regionprops function. Particularly, the "EquivDiameter", "MaxFeretProperties", and "MinFeretProperties" properties. Anything other measurement of diameter of an irregular object will likely be much more difficult to implement, unless you can find something on the Mathworks FileExchange.

Answer 2

[Image Analyst]

Get a binary image by thresholding the gray scale image. Then clean up a bit and call regionprops(). Assuming the cell walls are darker than the cells:

% Binarize the image by intensity thresholding.
binaryImage = grayImage > 128; % Or whatever.  Adjust number as needed or use imbinarize().
% Fill holes, in case there are any.
binaryImage = imfill(binaryImage, 'holes');
% Only keep blobs bigger than 100 pixels in area.
binaryImage = bwareaopen(binaryImage, 100); 
% Remove blobs touching border since you can't get reliable diameter if the whole blob is not there.
binaryImage = imclearborder(binaryImage);
% Measure equivalent circular diameters - diameter as if the blob were a perfect circle.
props = regionprops(binaryImage, 'EquivDiameter') % This is a structure.
% Extract Area fields into a double vector.
allDiameters = [props.EquivDiameter]
% Get the average
meanECD = mean(allDiameters)

[Amir Torabi]

Is it possible to implement the line intercept method for calculation of average diamtere?

This method is common for extracting average diamtere from microstructure images.

[Image Analyst]

Not exactly sure what it is but yes, you can do anything with MATLAB. If it's scanning down line by line and getting the average delta X of each cell, then I don't think that would be as accurate as working on the whole blobs as regionprops() does. You'd still have to call regionprops() to get the delta X distance but it's more complicated because you'd haver to do it on the labeled image, not the binary image to make sure each delta X measurement is applied to the correct blob.

[Cristian Mennella]

Sorry, instead of props.Area is props.EquivDiameter?or no?

AllDiameters=[props.EquivDiameter]

[Image Analyst]

Yes, you're right. My mistake. I'll correct it.