What units is the number in strel('disk', 22)?

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dilated = imdilate(ImagetoDilate,strel('disk', 22));
I have this line in my code to dilate the image, but I was wondering what units the 22 is? It says it is the radius but is it measured in centimeters, percentage, pixels or something else?

Accepted Answer

Walter Roberson
Walter Roberson on 16 Sep 2019
Edited: Walter Roberson on 16 Sep 2019
Or more correctly, memory locations, as the result is used in multiple contexts and makes no attempt to handle multiple color planes.
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Guillaume on 16 Sep 2019
Edited: Guillaume on 16 Sep 2019
You can easily look at the structuring element
>> s = strel('disk', 22)
s =
strel is a disk shaped structuring element with properties:
Neighborhood: [43×43 logical]
Dimensionality: 2
and you can see that the disk overlaps 43x43 pixels.
As for it being a disk:
>> imagesc(s.Neighborhood); colormap([0 0 0; 0.8 0.8 0.8]); axis('off')

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