Label/color each region in the image

Hi , How can I label each region in the attached image? As you can see, it has three (3) connected regions/faces. It is better to be labeled with different color.

Thanks in advance

Answer 1

[Image Analyst]

Try this:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
imtool close all;  % Close all imtool figures if you have the Image Processing Toolbox.
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 22;

% Read in a demo image.
folder = 'C:\Users\missc\Documents\Temporary';
baseFileName = 'a.jpg';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
if ~exist(fullFileName, 'file')
  % Didn't find it there.  Check the search path for it.
  fullFileName = baseFileName; % No path this time.
  if ~exist(fullFileName, 'file')
    % Still didn't find it.  Alert user.
    errorMessage = sprintf('Error: %s does not exist.', fullFileName);
    uiwait(warndlg(errorMessage));
    return;
  end
end
grayImage = imread(fullFileName);
% Get the dimensions of the image.  numberOfColorBands should be = 3.
[rows, columns, numberOfColorBands] = size(grayImage);
% Display the original color image.
subplot(2, 2, 1);
imshow(grayImage);
title('Original Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);

% Threshold so we can get a binary image to use as a mask.
binaryImage = grayImage < 100;
% Display the image.
subplot(2, 2, 2);
imshow(binaryImage);
axis on;
title('Binary Image', 'FontSize', fontSize);

% Get rid of white touching the border.
binaryImage = imclearborder(binaryImage, 4);
% Display the image.
subplot(2, 2, 3);
imshow(binaryImage);
axis on;
title('Faces Image', 'FontSize', fontSize);

[labeledImage, numberOfRegions] = bwlabel(binaryImage, 4);
coloredLabels = label2rgb (labeledImage, 'hsv', 'k', 'shuffle'); % pseudo random color labels
% Display the image.
subplot(2, 2, 4);
imshow(coloredLabels);
axis on;
title('Colored Label Image', 'FontSize', fontSize);

[missC]

Thanks sir, you really helped me out.

[missC]

Sir, How can I extract the boundaries of segmented/labeled from this image. Like this example it has three faces labeled with different number. Now, I just want to trace the edge or boundary for each face. I will be really grateful if you can help me. Thanks again

[Image Analyst]

boundaries = bwboundaries(binaryImage);

[missC]

Sir,I already apply bwboundaries to the labeled image but it was return the unrecognized value. According to the above image, I should 4 DIFFERENT extraction of each boundary or in other words boundary for each faces. How Can I do so. Really appreciate your help.

[Image Analyst]

Each face will have one boundary not 4, and not an unrecognized value. If you don't want 1 then try the FAQ: http://matlab.wikia.com/wiki/FAQ#How_do_I_find_.22kinks.22_in_a_curve.3F

[missC]

yes sir, I am so sorry because mislead to your understanding. That is what I meant, each face just consist of one boundary. Now I have 3 faces and I should have 3 boundaries. How can I do that sir? Or how to label only the edge not the face.

Really need your help. Thanks again

[Image Analyst]

boundaries = bwboundaries(binaryImage);

Then you can use the kink finding code I referred you to if you want to divide each boundary up into 4 straight segments. Or you can run along fitting a line and getting the histogram of the slopes and looking for 4 slopes that are found a lot (meaning when you're fitting pixels along one side only and not spanning across a corner).