how can i extract radius signature of a binary image?

i have a binary image and radius signature is distance between pixels on contour of object and its centroid. i use bwboundaries() but result is not good

i saw a example in matlab code of bwboundaries(),it used plot to show contour plot has best result but i dont need plot i need a matrix. i use blow code but my result is not same with matlab's example.

img4=zeros(size(img3));
[B,L] = bwboundaries(img3,'noholes');
for k = 1:length(B)
    boundary = B{k};
    for i=1:size(boundary,1)
        img4(boundary(i,1), boundary(i,2))=1;
    end
end

Answer 1

[Image Analyst]

Use regionprops to find the centroid, then use the Pythagorean theorem to get the distances between the boundary x,y coordinates and the centroid.

[Explorer]

I also need to do the same i.e. find the signature of binary image.

________________________________________________________________________

image = imread('C:\Users\Saeed Rattar\Desktop\aa_contour.jpg');

GRAY1 = rgb2gray(image);

threshold1 = graythresh(GRAY1);

BW1 = im2bw(GRAY1, threshold1);

stats = regionprops(BW1, 'Centroid')

c = stats.Centroid

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

I am getting this " 173.5000 1.0000 " as centroid. I think centroid should be single numerical value but why I am getting answer of 2 x 1 size.

How to use Pythagorean theorem to get the distances between the boundaries?

My binary image is like

[Image Analyst]

Use bwboundaries on the binary image

boundary = bwboundaries(binaryImage);
x = boundary(:,1);
y = boundary(:,2);
distances = sqrt((x - c(1)).^2 + (y - c(2)).^2);

[Explorer]

mage = imread('C:\Users\Explorer\Desktop\aa_contour.jpg');

GRAY1 = rgb2gray(image);

threshold1 = graythresh(GRAY1);

BW1 = im2bw(GRAY1, threshold1);

stats = regionprops(BW1, 'Centroid')

c = stats.Centroid

boundary = bwboundaries(BW1);

x = boundary(:,1);

y = boundary(:,2);

distances = sqrt((x - c(1)).^2 + (y - c(2)).^2)

____________________________________________________________________________

Error

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

stats = 2x1 struct array with fields:

    Centroid

c = 173.5 1

Index exceeds matrix dimensions. Error in signature (line 17) y = boundary(:,2);

___________________________________________________________________________

What should I do to correct this error?

[Image Analyst]

Use the debugger? What does "whos boundary" say? Is it an N rows by 2 columns array?

[Explorer]

>> whos

Name            Size                Bytes  Class      Attributes

BW            519x346              179574  logical              
boundary        3x1                 39824  cell                 
c               1x2                    16  double               
image         519x346x3            538722  uint8                
stats           2x1                   320  struct               
x               3x1                 39824  cell

[Explorer]

>> whos boundary

   Name          Size            Bytes  Class    Attributes

   boundary      3x1             39824  cell

[Image Analyst]

You have 3 blobs in your binary image, not just one. I don't know why. What are the other 2 blobs? You can get one by doing

thisBoundary = boundary{1}; % Or whatever blob you want.
x = thisBoundary(:,1);
y = thisBoundary(:,2);
distances = sqrt((x - c(1)).^2 + (y - c(2)).^2);

[Explorer]

Thanks for helping!

[Image Analyst]

Can you go ahead and accept it to close this out?

Answer 2

[Sabanam]

Thanks sir...its really helpful and the best answer to find radius signature...

Answer 3

[Sabanam]

Which formula used to find centroid in matlab?..Whenever i have read they are using mean of the point but is it right?