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Alessandro Mannini

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Computer Engineering - University of Florence - Italy

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24 Nov 2010 Screenshot Freeman Chain Code Gives Freeman chain code 8-connected representation of a boundary Author: Alessandro Mannini chain code, freeman, boundary, contour, representation, chaincode 104 19
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23 Apr 2014 Freeman Chain Code Gives Freeman chain code 8-connected representation of a boundary Author: Alessandro Mannini

Hi 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.

09 May 2012 Freeman Chain Code Gives Freeman chain code 8-connected representation of a boundary Author: Alessandro Mannini

Hi 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

17 Apr 2012 Freeman Chain Code Gives Freeman chain code 8-connected representation of a boundary Author: Alessandro Mannini

Hi 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

19 Mar 2011 Freeman Chain Code Gives Freeman chain code 8-connected representation of a boundary Author: Alessandro Mannini

Look 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.

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23 Apr 2014 Freeman Chain Code Gives Freeman chain code 8-connected representation of a boundary Author: Alessandro Mannini Mannini, Alessandro

Hi 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.

23 Apr 2014 Freeman Chain Code Gives Freeman chain code 8-connected representation of a boundary Author: Alessandro Mannini sujith

if 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.

21 Apr 2014 Freeman Chain Code Gives Freeman chain code 8-connected representation of a boundary Author: Alessandro Mannini Das, Monalisa

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

21 Feb 2014 Freeman Chain Code Gives Freeman chain code 8-connected representation of a boundary Author: Alessandro Mannini Max

Since 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);

07 Oct 2013 Freeman Chain Code Gives Freeman chain code 8-connected representation of a boundary Author: Alessandro Mannini missC

can 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

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