Can anyone provide me chain code for boundary detection in the matlab with explanation?

Chain code is used for boundary detection.

Answer 1

[Walter Roberson]

http://www.mathworks.com/matlabcentral/fileexchange/29518-freeman-chain-code

[Ekta Sharma]

Hello Sir Thank you very much for your reply but I am unable to run it as while I am giving input to this program it is giving error and I am unable to understand what is unwrap means in input.Kindly help.

[Walter Roberson]

unwrap: "if enable phase inversions are eliminated"

As for the errors: you will need to show us the error messages you are encountering.

Answer 2

[Image Analyst]

It's easy enough to do yourself. You can use bwboundaries() to get a list of boundary coordinates. Then loop over them and figure out which of the 8 directions the next pixel in the list is and assign a number from 1 to 8 to that pixel.

boundaries = bwboundaries()
x = boundaries(:, 2);
y = boundaries(:, 1);
for k = 1 : length(x)-1;
    thisX = x(k);
    thisY = y(k);
    nextX = x(k+1);
    nextY = y(k+1);
    if nextX == thisX
        % and so on.....
end

It's late here, so see if you can complete it yourself. It's easy.

[Ekta Sharma]

I am doing like this way but not getting the desired results.Can you help? clc; clear; close all; I=imread('tool.png'); % imshow(I) I2 = imcrop(I,[180 174 250 450]); figure imshow(I2) im2double(I2); t=graythresh(I2); BW=im2bw(I2,t); figure imshow(BW) J=bwperim(BW); B=im2double(J); imshow(B) [M, N]=size(B); p=7; q=6; h=5; s=4; t=3; u=2; v=1; w=0; for j=2:N-1 for i=2:M-1 if B(i,j)==1 fprintf('Element(%d,%d) = %d.\n',i,j,B(i,j)) x=i; y=j; while (x>=2 && y<=246) if B(x+1,y+1)==1 fprintf('The chain code for (%d,%d)= %d.\n',x,y,p) newx=x+1; newy=y+1; break; elseif B(x+1,y)==1 fprintf('The chain code for (%d,%d)= %d.\n',x,y,q) newx=x+1; newy=y; break; elseif B(x+1,y-1)==1 fprintf('The chain code for (%d,%d)= %d.\n',x,y,h) newx=x+1; newy=y-1; break; elseif B(x,y-1)==1 fprintf('The chain code for (%d,%d)= %d.\n',x,y,s) newx=x; newy=y-1; break; elseif B(x-1,y-1)==1 fprintf('The chain code for (%d,%d)= %d.\n',x,y,t) newx=x-1; newy=y-1; break; elseif B(x-1,y)==1 fprintf('The chain code for (%d,%d)= %d.\n',x,y,u) newx=x-1; newy=y; break; elseif B(x-1,y+1)==1 fprintf('The chain code for (%d,%d)= %d.\n',x,y,v) newx=x-1; newy=y+1; break; elseif B(x,y+1)==1 fprintf('The chain code for (%d,%d)= %d.\n',x,y,w) newx=x; newy=y+1; break; end end end end end