MATLAB: Label/color each region in the image

image processingImage Processing Toolbox

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

Best Answer

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);

Related Solutions

MATLAB: Crop dark area and display the face only

Convert to grayscale and then threshold and find the bounding box

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
imtool close all;  % Close all imtool figures.
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
% Read in the color image.
folder = pwd;
baseFileName = 'm2.bmp';
% 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
rgbImage = imread(fullFileName);
% Get the dimensions of the image.  numberOfColorBands should be = 3.
[rows, columns, numberOfColorBands] = size(rgbImage);
% Display the original color image.
subplot(2, 3, 1);
imshow(rgbImage, []);
axis on;
title('Original Color Image', 'FontSize', fontSize);
drawnow;
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Histogram the red channel, but there is a huge spike at 255 so let's not count those.
subplot(2, 3, 2);
grayImage = rgb2gray(rgbImage);
imshow(grayImage, []);
title('Gray Scale version', 'FontSize', fontSize);
subplot(2, 3, 3);
histogram(grayImage(grayImage<255))
grid on;
title('Histogram of Gray Scale Image', 'FontSize', fontSize);
someThresholdValue = 150;
binaryImage = grayImage > someThresholdValue;
% Take largest blob
binaryImage = bwareafilt(binaryImage, 1);
subplot(2, 3, 4);
imshow(binaryImage);
grid on;
title('Binary Image', 'FontSize', fontSize);
% Label the binary image.
labeledImage = bwlabel(binaryImage);
props = regionprops(labeledImage, 'BoundingBox');
bbox = props.BoundingBox
croppedImageRGB = imcrop(rgbImage, bbox);
subplot(2, 3, 5);
imshow(croppedImageRGB);
grid on;
title('Cropped RGB Image', 'FontSize', fontSize);
% Gray scale version of cropped image
croppedImageGray = imcrop(grayImage, bbox);
subplot(2, 3, 6);
imshow(croppedImageGray);
grid on;
title('Cropped Gray Scale Image', 'FontSize', fontSize);

MATLAB: How to cut out an area that I’ve created a boundary to

Close. Here, try this:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
imtool close all;  % Close all imtool figures.
clear;  % Erase all existing variables.
workspace;  % Make sure the workspace panel is showing.
format longg;
format compact;
fontSize = 20;
% Change the current folder to the folder of this m-file.
if(~isdeployed)
  cd(fileparts(which(mfilename)));
end
  
% Check that user has the Image Processing Toolbox installed.
hasIPT = license('test', 'image_toolbox');
if ~hasIPT
  % User does not have the toolbox installed.
  message = sprintf('Sorry, but you do not seem to have the Image Processing Toolbox.\nDo you want to try to continue anyway?');
  reply = questdlg(message, 'Toolbox missing', 'Yes', 'No', 'Yes');
  if strcmpi(reply, 'No')
    % User said No, so exit.
    return;
  end
end
% Read in a demo image.
folder = 'C:\Users\Student\Documents\Temporary';
baseFileName = '2z3nja1.jpg';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
  % File doesn't exist -- 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 in the search path folders.', fullFileName);
    uiwait(warndlg(errorMessage));
    return;
  end
end
grayImage = rgb2gray(imread(fullFileName));
% Get the dimensions of the image.  
% numberOfColorBands should be = 1.
[rows columns numberOfColorBands] = size(grayImage);
% Display the original gray scale image.
subplot(2, 2, 1);
imshow(grayImage, []);
title('Original Grayscale Image', 'FontSize', fontSize);
% Enlarge figure to full screen.

set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Give a name to the title bar.

set(gcf,'name','Demo by ImageAnalyst','numbertitle','off') 
% Let's compute and display the histogram.
[pixelCount grayLevels] = imhist(grayImage);
subplot(2, 2, 2); 
bar(pixelCount);
grid on;
title('Histogram of original image', 'FontSize', fontSize);
xlim([0 grayLevels(end)]); % Scale x axis manually.
% Find border and mask it off
binaryImage = grayImage == 255;
% Display the image.



subplot(2, 2, 3);
imshow(binaryImage, []);
title('Original Binary Image', 'FontSize', fontSize);
% Get just hte border pixels.
borderImage = logical(binaryImage - imclearborder(binaryImage));
% Move the outer edge in a little bit.
borderImage = imdilate(borderImage, true(7));
% Display the image.
subplot(2, 2, 4);
imshow(borderImage, []);
title('Border Pixels Image', 'FontSize', fontSize);
% Start a new figure.
figure;
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Give a name to the title bar.
set(gcf,'name','Demo by ImageAnalyst','numbertitle','off') 
% Erase border pixels.
grayImage(borderImage) = 0;
% Display the image.
subplot(2, 2, 1);
imshow(grayImage, []);
title('Masked Image', 'FontSize', fontSize);
% Threshold for dark pixels.
binaryImage3 = (grayImage > 0) & (grayImage < 125); % Threshold to isolate lung tissue
% Get the two largest blobs.
[labeledImage numberOfBlobs] = bwlabel(binaryImage3);
blobMeasurements = regionprops(labeledImage, 'Area');
allAreas = [blobMeasurements.Area];
[sortedAreas sortIndices] = sort(allAreas, 'descend');
% Get a list of the blobs that meet our criteria and we need to keep. 
keeperIndexes = [sortIndices(1), sortIndices(2)]; 
% Extract only those blobs that meet our criteria, and 
% eliminate those blobs that don't meet our criteria. 
% Note how we use ismember() to do this.
keeperBlobsImage = ismember(labeledImage, keeperIndexes); 
% Binarize and fill holes.
binaryImage3 = imfill(keeperBlobsImage>0, 'holes');
% Display the image.
subplot(2, 2, 2);
imshow(binaryImage3, []);
title('Two Largest Regions', 'FontSize', fontSize);
% Re-label with only the keeper blobs kept.
labeledImage = bwlabel(keeperBlobsImage, 8);     % Label each blob so we can make measurements of it
% Find outer boundaries and trace over image.
% bwboundaries() returns a cell array, where each cell contains the row/column coordinates for an object in the image.
% Plot the borders of two largest regions returned by bwboundaries.
subplot(2, 2, 3); 
imshow(grayImage, []);
title('Outlines, from bwboundaries()', 'FontSize', fontSize);
hold on;
boundaries = bwboundaries(binaryImage3);  
numberOfBoundaries = size(boundaries);
for k = 1 : numberOfBoundaries
  thisBoundary = boundaries{k};
  plot(thisBoundary(:,2), thisBoundary(:,1), 'g', 'LineWidth', 2);
end
hold off;
% Now let's extract out just the lungs.
maskedImage = zeros(rows, columns, 'uint8'); % Initialize.
maskedImage(binaryImage3) = grayImage(binaryImage3);
subplot(2, 2, 4); 
imshow(maskedImage, []);
title('Lungs Masked', 'FontSize', fontSize);

Best Answer

Related Solutions

MATLAB: Crop dark area and display the face only

MATLAB: How to cut out an area that I’ve created a boundary to

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