tree-ring detection !!!

It's a binary picture of a wood disk.

1. Is there a way to detect the white and black boundaries?

2. I want to get rid of the black noise that exists in the white area.

is there any other way to make clearer binary image?

we use matlab.

[KALYAN ACHARJYA]

Have you tried with Morphological operation?

[Taelee Kim]

Yesss, i tried imerode, imdilate, imopen operation.

but, it doesn't work well.

Because, that image have scratches ( caused by sandpaper machine).

When morphological shape is bigger than 5, thin tree ring is discovered by Morphological shape.

plz...

Answer 1

[KSSV]

How about this approach?

I = imread('image.png') ; 
I1 = imcrop(I) ;    % cropping the required part 
% imshow(I1)
I2 = rgb2gray(I1) ; 
[y,x] = find(I2==0) ; 

N = 15 ; 

%% Get Bounding box
x0 = min(x) ; x1 = max(x) ;
y0 = min(y) ; y1 = max(y) ;
% length and breadth 
L = abs(x1-x0) ;
B = abs(y1-y0) ;
% center bounding box
C = [x0+B/2 y0+L/2] ;
%% Get distances of the points from center of bounding box
data = repmat(C,[length(x),1])-[x,y] ;
dist = sqrt(data(:,1).^2+data(:,2).^2);
%% Classify the points into circles 
nbins = 15 ;   % number of circles you want
[N,edges,bin] = histcounts(dist,nbins) ;
% plot the classified circle points for check 
figure(1)
imshow(I2)
hold on
for i = 1:nbins
    plot((x(bin==i)),y(bin==i),'.','color',rand(1,3)) ;
end

%% Circle's radii and center 
Circ = cell(nbins,1) ;
for i = 1:nbins 
    [xc1,yc1,R] = circfit(x(bin==i),y(bin==i)) ;
    Circ{i} = [xc1 yc1 R] ;
end
figure(2)
imshow(I2)
hold on
th = linspace(0,2*pi) ;
for i = 1:nbins
    xc = Circ{i}(1)+Circ{i}(3)*cos(th) ;
    yc = Circ{i}(2)+Circ{i}(3)*sin(th) ;
    plot(xc,yc,'color',rand(1,3),'linewidth',3) ;
end

[Metin EKEN]

Hi, i am working on this code but I get an error message (Unrecognized function or variable 'circfit'.). I can't add the "circfit" function. can you help me?

[KSSV]

@Metin EKEN you can download the circfit function from here:

https://in.mathworks.com/matlabcentral/fileexchange/56412-circfit?requestedDomain=

[Image Analyst]

@Metin EKEN You can use this

https://matlab.fandom.com/wiki/FAQ#How_can_I_fit_a_circle_to_a_set_of_XY_data.3F

%===========================================================================================================================================
function [xCenter, yCenter, radius, a] = circlefit(x, y)
% circlefit(): Fits a circle through a set of points in the x - y plane.
% USAGE :
% [xCenter, yCenter, radius, a] = circlefit(X, Y)
% The output is the center point (xCenter, yCenter) and the radius of the fitted circle.
% "a" is an optional output vector describing the coefficients in the circle's equation:
%     x ^ 2 + y ^ 2 + a(1) * x + a(2) * y + a(3) = 0
% by Bucher Izhak 25 - Oct - 1991

numPoints = numel(x);
xx = x .* x;
yy = y .* y;
xy = x .* y;
A = [sum(x),  sum(y),  numPoints;
    sum(xy), sum(yy), sum(y);
    sum(xx), sum(xy), sum(x)];
B = [-sum(xx + yy) ;
    -sum(xx .* y + yy .* y);
    -sum(xx .* x + xy .* y)];
a = A \ B;
xCenter = -.5 * a(1);
yCenter = -.5 * a(2);
radius  =  sqrt((a(1) ^ 2 + a(2) ^ 2) / 4 - a(3));
end

[Metin EKEN]

Thanks for recommends. Actualy I have a different problem. İ'm using various function to counting tree age rings, but results not good. Can you tell me, which function am ı use.