version 1.0.0.0 (2.35 KB) by
Alessandro Mannini

Gives Freeman chain code 8-connected representation of a boundary

usage:

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[cc] = chaincode(b,u)

INPUT:

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b - boundary as np-by-2 array

unwrap - (optional, default=false) unwrap code

OUTPUT:

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cc is a structure with the following fields:

cc.code - 8-connected Freeman chain code 1-by-np

cc.x0,cc.y0 - coordinates of start point

cc.ucode - unwrapped 8-connected Freeman chain code

Alessandro Mannini (2021). Freeman Chain Code (https://www.mathworks.com/matlabcentral/fileexchange/29518-freeman-chain-code), MATLAB Central File Exchange. Retrieved .

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Raffaele SpieziaEvangelia AthanasiouNewbigginTya Chuanromaneeathira k smohamed kamelKIRTI KPlease reply this is really very urgent

Girish MallyaJesse LameShivadatt ChameRespected sir,

when i run this code:

C=imread('thinnw.jpg');

C(C<225)=0;

s=strel('disk',4,0);%Structuring element

D=~im2bw(C);%binary Image

F=imerode(D,s);%Erode the image by structuring element

figure,imshow(C);title('Original Image');

figure,imshow(D);title('Binary Image');

AH=D-F;

figure,imshow(AH);

title('Boundary extracted Image');

h=fspecial('average',9);

g=imfilter(D,h,'replicate');

gb=im2bw(g,0.5);

B=bwboundaries(gb,'noholes');

d=cellfun('length',B);

[maxd,k]=max(d);

b=B{1};

[M,N]=size(g);

g=bound2im(b,M,N,min(b(:,1)),min(b(:,2)));

[s,su]=bsubsamp(b,50);

cc=chaincode(su);

i am getting same chain code for different A-Z characters please help me....urgent requirement...

Shivadatt ChameRespected sir,

this chain code i run and getting same code for different characters also...please suggest me...

Shivadatt ChameDear sir

i am using chain code for different characters A-Z but i want every characters chain code would be same size.

i am not getting the chain code of same size please suggest me.

Christin PanjaitanDear Alessandro,

I have read your code about chaincode.

I have question about the equation below :

idx=3*(dy+1)+(dx+1)=3dy+dx+4 (adding 1 to have idx starting % from 1)

You made the equation for 8-connected.

Why did you multiply dy with 3 ?

How about 4-Connected ?

How do I form the equation ?

Shivadatt ChameRespected sir,

i want to apply chain code on Character image R but using this function how to apply on image.....suggest me...

Munika Patelwork awsomee...

Divya Kakadiyahow to get value of b passed as parameter? Thanking in advanced

Xia LinfarinazcspitMaximum recursion limit of 500 reached. Use set(0,'RecursionLimit',N)

to change the limit. Be aware that exceeding your available stack space can

crash MATLAB and/or your computer.

Error in ==> imformats>find_in_registry

what should i do now??

Monalisa DasHi, I keep getting the error "the xpression to the left of the equals sign is not a valid target" when I try to use the [cc]= chaincode(b,u)...what am I doing wrong?

Alessandro ManniniHi Monalisa, see the description and previous comments. Main steps are:

1) get the contour of the image

2) put coords of contour points in b

3) call chaincode(b,true/false)

Note: the contour must be 8-connected tha is, given a point on the boundary it must have only two neighbors, the previous and the next. There can be NO forks.

sujithif u don't want to unwrap,just change function name to [cc] = chaincode(b)

and remove the unwrapping section from program.trace the boundary of your image using 'bwtraceboundary' function and input it to chain code function.

Monalisa DasHi, could you tell me how to use this function to get chaincode for an image? Thanks!

MaxSince a few people have asked how to get a chain code from an image I have written a simple script to do this.

You can download the script here: https://raw2.github.com/maximilianallan/mk_chain/master/mk_chain.m

The script is really simple and makes some assumptions about a single contour in the image but should be easy to modify if needed.

Usage:

>> chain = mk_chain('path/to/image.png');

>> [cc] = chaincode(chain);

missCcan anyone give me an example on how to call or use this function. I am totally new on matlab and need to see how this chaincode works? many thanks and really appreciate it

AntonWorked fine for me, thank you very much for the comments, they were VERY helpful!

Daurat Sinagai was running this function and i get output like this :

CC =

x0:0

y0:0

code:[209x1 double], would you explain it for me ?

ranawould you tell me please the exact steps to run this code ??

than you :)

Alessandro ManniniHi Ann, look to my previous comments (ex. 19/3/2011) the b parameter is an array containing coords of boundary points that should be 8-connected. 8-connected means that if Bn is the n-th element of b and Bn+1 the next their x y coords should satisfy this relations: | Xn - Xn+1 |<=1 AND | Yn - Yn+1 |<=1. Start checking that with a simple example. Regards Alessandro

Anni am trying to use this code on the image but i am getting the error "Curve isn't 8-connected in elements: "

what to do?

Alessandro ManniniHi Frb, please note than b contains coords of boundary points order so that they are 8-connected. The find function you use return coords of boundary points but in a different order. From Matlab Help seems it scans matrix column by column. Best regards Alessandro

Frbhello,

I checked this code, seems very useful but I have problem, I give this piece of code to make it 8-connected:

I=imread('im1.jpg');

BW1=im2bw(I);

BW1=~BW1;

BW2 = bwperim(BW1,8);

image=BW2;

[x y]=find(image==1);

b=[x y];

and then I put the result in b,

when I run the code error applies and says Curve isn''t 8-connected in elements. I appreciate any help.

Kind Regards,

Fariba

Anushif i have an image what's the procedure to find the chain code for that particular image !

hamzaThanks for your great work, and I have a question :-

I have image called XYZ.png and I passed that images to this function but I found an error.

Please help me in how to execute this function.

maddyi had a skeleton with me which i want to give as a input to this chaincode..and when i tried to do that...i am getting that subscript indices are must be either positive or real...please somebody help me in resolving this...

Amri have a silhouette for human image(http://i.imgur.com/fTwkZ.png) and I put the image boundary in an array and then i passed it to the Freeman Chain Code function. this image shows the body boundary is connected to each other but in real it gives me this error

"Curve isn't 8-connected in elements:

idx -> 350

idx -> 700

idx -> 1050

idx -> 1400

....

"

so can any one help me please? :)

Alessandro ManniniLook at description inside source code:

% b - boundary as np-by-2 array;

% np is the number of pixels and each element is a pair (y,x) of

% pixel coordinates

For example, if you have 4 points p=(y,x) like this p1=(5,1);p2=(5,2);p3=(4,2);p4=(3,1) b is:

b = [ 5 1;5 2;4 2;3 1]

note that points must be 8-connected.

Manhalhi,

what should be the input for "b"?

is it an image or what ??

need help as soon as possible pls ..

thanx

Santhosh RA very nice self explanatory code!!

Was very useful for my project.

Great job!!!!!!!!!