Find radius of circle and find curvature from images

Hello,

I am struggling to find 1) radius of the below two circles and 2) curvature of the boundary.

About 1) problem, I tried several builin function like starts = regionprops(), viscircles(centers,radii), and imfindcircles(), but apprently I am missing something.

I think that this issue could happen because more than half of the circle is not presented in the image.

About 2) problem,

I want to find the radius of the curvature in the yellow region. Using given codes in this community, I could find the boundary line, but I am unsure what to do next.

Any help, hints or helpful links would be appreciated.

Answer 1

[Sulaymon Eshkabilov]

Hi,

Have you reviewed this help doc of mathworks on circle identification in images?

https://www.mathworks.com/help/images/detect-and-measure-circular-objects-in-an-image.html

[autumn]

Hi,

I tried using the first image like below.

clear all
clc
I=imread('Picture1.png');  
B=rgb2gray(I); 
B = imbinarize(B);  imshow(B); hold on
[centers,radii] = imfindcircles('ObjectPolarity','dark', ...
          'Sensitivity',0.92,'Method','twostage');

viscircles(centers,radii);
hold off

but I had this error. What does this mean?..

----------------------------------------

Error using imfindcircles>parseInputs (line 240)

The value of 'Image' is invalid. Expected input number 1, A, to be one of these types:

uint8, uint16, double, logical, single, int16

Error in imfindcircles (line 142)

parsedInputs = parseInputs(varargin{:});