Freeman chain code

Freeman chain code algorithm to extract boundaries of objects in a binary image. Help, doc, examples included. + Some bwmorph operators.
303 Downloads
Updated 29 May 2023

Editor's Note: This file was selected as MATLAB Central Pick of the Week

Use on binary images only (use imbinarize to binarize your image).
Check the use examples provided in Freeman_chain_code_examples.m to help / inspire you.
Recent update adds some image processing toolbox bwmorph "spare operators" you might recognize (dilate_image, erode_image, image_bw_remove, open_image, close_image), updated examples and images.
image_bw_remove function looks specially interesting to get quickly and all at once your binary image boundaries.
Please rate if it helped you, thanks. ;-)
% Freeman_chain_code : function to extract the contour of a given shape using
% Freeman chain code. For binary images only.
%
% Author & support : nicolas.douillet (at) free.fr, 2005-2023.
%
% Reference
%
% Freeman H, Computer Processing of Line-Drawing Images,
% ACM Computing Surveys, Vol. 6, No.1, 1974, pp57-97.
%
% Inputs
%
% - I : binary (0/1) image where 0 pixels correspond to the black
% background, and 1 pixels correspond to the object(s) / shape(s) to
% segment.
%
% - option_display : either logical, true/false or numeric 1/0.
%
% Outputs
%
% - bound_img : binary (0/1) image of the input image boundaries. size(bound_img) = size(I).
%
% - X0 : cell array of integer vectors of double, the boundaries initial pixels coordinates.
%
% - Code : cell array of integer vectors of double, the boundaries Freeman coding vectors.
%
% - bound_coord : cell array of integer vectors of double, the boundaries pixels coordinates.
%
% Current known limitations
%
% - Only extract the shapes outer boundaries / do not extract one shape inner parts

Cite As

Nicolas Douillet (2024). Freeman chain code (https://github.com/NicolasDouillet/Freeman_chain_code/releases/tag/v3.2), GitHub. Retrieved .

MATLAB Release Compatibility
Created with R2019b
Compatible with any release
Platform Compatibility
Windows macOS Linux

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Version Published Release Notes
3.2

See release notes for this release on GitHub: https://github.com/NicolasDouillet/Freeman_chain_code/releases/tag/v3.2

3.1

See release notes for this release on GitHub: https://github.com/NicolasDouillet/Freeman_chain_code/releases/tag/v3.1

3.0

See release notes for this release on GitHub: https://github.com/NicolasDouillet/Freeman_chain_code/releases/tag/v3.0

2.0

See release notes for this release on GitHub: https://github.com/NicolasDouillet/Freeman_chain_code/releases/tag/v2.0

1.1

See release notes for this release on GitHub: https://github.com/NicolasDouillet/Freeman_chain_code/releases/tag/v1.1

1.0.1

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1.0.0

To view or report issues in this GitHub add-on, visit the GitHub Repository.
To view or report issues in this GitHub add-on, visit the GitHub Repository.