How to annotate borders with different colors?

clear all;
close all;
clc;

a=im2bw(imread('taskD_tag1.tif'));
c=im2bw(imread('taskD_tag2.tif'));

L3 = rangefilt(a);
L4 = rangefilt(c);

montage({L3})

How to annotate border with different colors? (e.g. yellow and blue) Here are the images that are binarised and filter.

Answer 1

[Image Analyst]

OK, here's a full demo for you.

% Demo by Image Analyst
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 16;

%===============================================================================
% Get the name of the image the user wants to use.
baseFileName = 'cards.JPEG';
folder = pwd;
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
    % The file doesn't exist -- didn't find it there in that folder.
    % Check the entire search path (other folders) for the file by stripping off the folder.
    fullFileNameOnSearchPath = baseFileName; % No path this time.
    if ~exist(fullFileNameOnSearchPath, '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

%===================================================================================================================
% Read in image.
rgbImage = imread(fullFileName);
% Get the dimensions of the image.
[rows, columns, numberOfColorChannels] = size(rgbImage)
% Display image.
subplot(2, 2, 1);
imshow(rgbImage, []);
impixelinfo;
axis on;
caption = sprintf('Original RGB Image\n%s', baseFileName);
title(caption, 'FontSize', fontSize, 'Interpreter', 'None');
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.
% Set up figure properties:
% Enlarge figure to full screen.
g = gcf;
g.WindowState = "maximized";
% Get rid of tool bar and pulldown menus that are along top of figure.
% set(gcf, 'Toolbar', 'none', 'Menu', 'none');
% Give a name to the title bar.
set(gcf, 'Name', 'Demo by ImageAnalyst', 'NumberTitle', 'Off')
drawnow;

%=========================================================================================================================
% Threshold the image to create a mask of the blue objects
[blueMask,maskedRGBImage] = createBlueMask(rgbImage);
% Get rid of particles less than 1000 pixels.
% props = regionprops(mask, 'Area'); % Measure areas of our initial mask to determine areas of LED and possible noise.
% allAreas = sort([props.Area])
% mask = bwareaopen(mask, 1000);
% Take the largest blob only.
blueMask = bwareafilt(blueMask, 1);
% Fill any holes in the blobs.
blueMask = imfill(blueMask, 'holes');
% Display the mask image.
subplot(2, 2, 2);
imshow(blueMask, []);
impixelinfo;
axis('on', 'image');
title('Blue Mask Image', 'FontSize', fontSize);
drawnow;

%=========================================================================================================================
% Threshold the image to create a mask of the blue objects
[yellowMask,maskedRGBImage] = createYellowMask(rgbImage);
% Get rid of particles less than 1000 pixels.
% props = regionprops(yellowMask, 'Area'); % Measure areas of our initial mask to determine areas of LED and possible noise.
% allAreas = sort([props.Area])
% mask = bwareaopen(yellowMask, 1000);
% Take the largest blob only.
yellowMask = bwareafilt(yellowMask, 1);
% Fill any holes in the blobs.
yellowMask = imfill(yellowMask, 'holes');
% Display the mask image.
subplot(2, 2, 3);
imshow(yellowMask, []);
impixelinfo;
axis('on', 'image');
title('Yellow Mask Image', 'FontSize', fontSize);
drawnow;

%=========================================================================================================================
% Get the boundaries
% Plot the borders of all the blobs in the overlay above the original grayscale image 
% using the coordinates returned by bwboundaries().
% bwboundaries() returns a cell array, where each cell contains the row/column coordinates for an object in the image.
subplot(2, 2, 4);
imshow(rgbImage); % Optional : show the original image again.  Or you can leave the binary image showing if you want.
% Here is where we actually get the boundaries for each blob.
blueBoundaries = bwboundaries(blueMask);
yellowBoundaries = bwboundaries(yellowMask);
% boundaries is a cell array - one cell for each blob.
% In each cell is an N-by-2 list of coordinates in a (row, column) format.  Note: NOT (x,y).
% Column 1 is rows, or y.    Column 2 is columns, or x.
numberOfBoundaries = size(blueBoundaries, 1); % Count the boundaries so we can use it in our for loop
% Here is where we actually plot the boundaries of each blob in the overlay.
hold on; % Don't let boundaries blow away the displayed image.
for k = 1 : numberOfBoundaries
    % Plot blue boundaries in red.
    thisBoundary = blueBoundaries{k}; % Get boundary for this specific blob.
    x = thisBoundary(:,2); % Column 2 is the columns, which is x.
    y = thisBoundary(:,1); % Column 1 is the rows, which is y.
    plot(x, y, 'r-', 'LineWidth', 2); % Plot boundary in red.
    % Plot yellow boundaries in magenta.
    thisBoundary = yellowBoundaries{k}; % Get boundary for this specific blob.
    x = thisBoundary(:,2); % Column 2 is the columns, which is x.
    y = thisBoundary(:,1); % Column 1 is the rows, which is y.
    plot(x, y, 'm-', 'LineWidth', 2); % Plot boundary in red.
end
hold off;
caption = sprintf('Outlines, from bwboundaries()'); 
title(caption, 'FontSize', fontSize); 
axis('on', 'image'); % Make sure image is not artificially stretched because of screen's aspect ratio.

%=========================================================================================================================
% Display image.
subplot(2, 2, 1);
imshow(rgbImage, []);
impixelinfo;
axis on;
caption = sprintf('Original RGB Image\n%s', baseFileName);
title(caption, 'FontSize', fontSize, 'Interpreter', 'None');
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.

%=========================================================================================================================
function [BW,maskedRGBImage] = createBlueMask(RGB)
%createMask  Threshold RGB image using auto-generated code from colorThresholder app.
%  [BW,MASKEDRGBIMAGE] = createMask(RGB) thresholds image RGB using
%  auto-generated code from the colorThresholder app. The colorspace and
%  range for each channel of the colorspace were set within the app. The
%  segmentation mask is returned in BW, and a composite of the mask and
%  original RGB images is returned in maskedRGBImage.
% Auto-generated by colorThresholder app on 14-Dec-2022
%------------------------------------------------------
% Convert RGB image to chosen color space
I = rgb2hsv(RGB);
% Define thresholds for channel 1 based on histogram settings
channel1Min = 0.453;
channel1Max = 0.817;
% Define thresholds for channel 2 based on histogram settings
channel2Min = 0.338;
channel2Max = 1.000;
% Define thresholds for channel 3 based on histogram settings
channel3Min = 0.000;
channel3Max = 1.000;
% Create mask based on chosen histogram thresholds
sliderBW = (I(:,:,1) >= channel1Min ) & (I(:,:,1) <= channel1Max) & ...
    (I(:,:,2) >= channel2Min ) & (I(:,:,2) <= channel2Max) & ...
    (I(:,:,3) >= channel3Min ) & (I(:,:,3) <= channel3Max);
BW = sliderBW;
% Initialize output masked image based on input image.
maskedRGBImage = RGB;
% Set background pixels where BW is false to zero.
maskedRGBImage(repmat(~BW,[1 1 3])) = 0;
end

%======================================================================================================================
function [BW,maskedRGBImage] = createYellowMask(RGB)
%createMask  Threshold RGB image using auto-generated code from colorThresholder app.
%  [BW,MASKEDRGBIMAGE] = createMask(RGB) thresholds image RGB using
%  auto-generated code from the colorThresholder app. The colorspace and
%  range for each channel of the colorspace were set within the app. The
%  segmentation mask is returned in BW, and a composite of the mask and
%  original RGB images is returned in maskedRGBImage.
% Auto-generated by colorThresholder app on 14-Dec-2022
%------------------------------------------------------
% Convert RGB image to chosen color space
I = rgb2hsv(RGB);
% Define thresholds for channel 1 based on histogram settings
channel1Min = 0.066;
channel1Max = 0.346;
% Define thresholds for channel 2 based on histogram settings
channel2Min = 0.113;
channel2Max = 1.000;
% Define thresholds for channel 3 based on histogram settings
channel3Min = 0.808;
channel3Max = 1.000;
% Create mask based on chosen histogram thresholds
sliderBW = (I(:,:,1) >= channel1Min ) & (I(:,:,1) <= channel1Max) & ...
    (I(:,:,2) >= channel2Min ) & (I(:,:,2) <= channel2Max) & ...
    (I(:,:,3) >= channel3Min ) & (I(:,:,3) <= channel3Max);
BW = sliderBW;
% Initialize output masked image based on input image.
maskedRGBImage = RGB;
% Set background pixels where BW is false to zero.
maskedRGBImage(repmat(~BW,[1 1 3])) = 0;
end

Answer 2

[millercommamatt]

This example from the Documentation includes a way to do this.

https://www.mathworks.com/help/images/correcting-nonuniform-illumination.html

Answer 3

[Image Analyst]

Here is a snippet to draw boundaries about your blobs in a binary image. You can change the color to whatever you want in the call to plot():

% Plot the borders of all the blobs in the overlay above the original grayscale image 
% using the coordinates returned by bwboundaries().
% bwboundaries() returns a cell array, where each cell contains the row/column coordinates for an object in the image.
imshow(originalImage); % Optional : show the original image again.  Or you can leave the binary image showing if you want.
% Here is where we actually get the boundaries for each blob.
boundaries = bwboundaries(mask);
% boundaries is a cell array - one cell for each blob.
% In each cell is an N-by-2 list of coordinates in a (row, column) format.  Note: NOT (x,y).
% Column 1 is rows, or y.    Column 2 is columns, or x.
numberOfBoundaries = size(boundaries, 1); % Count the boundaries so we can use it in our for loop
% Here is where we actually plot the boundaries of each blob in the overlay.
hold on; % Don't let boundaries blow away the displayed image.
for k = 1 : numberOfBoundaries
    thisBoundary = boundaries{k}; % Get boundary for this specific blob.
    x = thisBoundary(:,2); % Column 2 is the columns, which is x.
    y = thisBoundary(:,1); % Column 1 is the rows, which is y.
    plot(x, y, 'r-', 'LineWidth', 2); % Plot boundary in red.
end
hold off;
caption = sprintf('%d Outlines, from bwboundaries()', numberOfBoundaries); 
fontSize = 15;
title(caption, 'FontSize', fontSize); 
axis('on', 'image'); % Make sure image is not artificially stretched because of screen's aspect ratio.

[Ahmad Muzaffar Zafriy]

Any tips to replace the boundaries with the original RGB image?

[Image Analyst]

Not sure what you mean. Where are the boundaries? And what image do you want to pull original RGB values from and paste into? Like put RGB values into the binary image along the outline of the colored cards? If so, why would you want to do that? If you could label the binary outline image and then use label2rgb to make each outline the color you want.

[Ahmad Muzaffar Zafriy]

I am trying to replicate, what this person tried with his RGB image...

https://www.mathworks.com/matlabcentral/answers/1842668-how-to-annotate-border-around-original-rgb-image

[Image Analyst]

He outlined them in green so you'd just do this:

% Plot the borders of all the blobs in the overlay above the original grayscale image 
% using the coordinates returned by bwboundaries().
% bwboundaries() returns a cell array, where each cell contains the row/column coordinates for an object in the image.
imshow(originalImage); % Optional : show the original image again.  Or you can leave the binary image showing if you want.
% Here is where we actually get the boundaries for each blob.
boundaries = bwboundaries(mask);
% boundaries is a cell array - one cell for each blob.
% In each cell is an N-by-2 list of coordinates in a (row, column) format.  Note: NOT (x,y).
% Column 1 is rows, or y.    Column 2 is columns, or x.
numberOfBoundaries = size(boundaries, 1); % Count the boundaries so we can use it in our for loop
% Here is where we actually plot the boundaries of each blob in the overlay.
hold on; % Don't let boundaries blow away the displayed image.
for k = 1 : numberOfBoundaries
    thisBoundary = boundaries{k}; % Get boundary for this specific blob.
    x = thisBoundary(:,2); % Column 2 is the columns, which is x.
    y = thisBoundary(:,1); % Column 1 is the rows, which is y.
    plot(x, y, 'g-', 'LineWidth', 2); % Plot boundary in green.
end
hold off;
caption = sprintf('%d Outlines, from bwboundaries()', numberOfBoundaries); 
fontSize = 15;
title(caption, 'FontSize', fontSize); 
axis('on', 'image'); % Make sure image is not artificially stretched because of screen's aspect ratio.

[Ahmad Muzaffar Zafriy]

I can replace the code above, with the original and binary image? originalImage and mask?

Unrecognized function or variable 'mask'.

imshow(originalrgbphoto.jpg);

boundaries = bwboundaries(mask); %???

[Image Analyst]

Yes, use whatever names you gave your original RGB image and your binary image (mask). But if you use the filename in imshow() you'll have to enclose it in quotes. Otherwise use the uint8 variable name.

[Ahmad Muzaffar Zafriy]

Okay, but I'm getting red, instead of blue or yellow, for the image...

clear all;
close all;
clc;

% Plot the borders of all the blobs in the overlay above the original grayscale image 
% using the coordinates returned by bwboundaries().
% bwboundaries() returns a cell array, where each cell contains the row/column coordinates for an object in the image.
% Optional : show the original image again.  Or you can leave the binary image showing if you want.
% Here is where we actually get the boundaries for each blob.
imshow("rgb.jpg")
BW = imread("rgb.jpg");
BW= im2bw(BW);
boundaries = bwboundaries(BW);
% boundaries is a cell array - one cell for each blob.
% In each cell is an N-by-2 list of coordinates in a (row, column) format.  Note: NOT (x,y).
% Column 1 is rows, or y.    Column 2 is columns, or x.
numberOfBoundaries = size(boundaries, 1); % Count the boundaries so we can use it in our for loop
% Here is where we actually plot the boundaries of each blob in the overlay.
hold on; % Don't let boundaries blow away the displayed image.
for k = 1 : numberOfBoundaries
    thisBoundary = boundaries{k}; % Get boundary for this specific blob.
    x = thisBoundary(:,2); % Column 2 is the columns, which is x.
    y = thisBoundary(:,1); % Column 1 is the rows, which is y.
    plot(x, y, 'r-', 'LineWidth', 2); % Plot boundary in red.
end
hold off;
caption = sprintf('%d Outlines, from bwboundaries()', numberOfBoundaries); 
fontSize = 15;
title(caption, 'FontSize', fontSize); 
axis('on', 'image'); % Make sure image is not artificially stretched because of screen's aspect ratio.

[Ahmad Muzaffar Zafriy]

[Image Analyst]

The problem is you're using this function:

BW= im2bw(BW);

Why do you think that will get you the two colored cards? Out of all the things in that image, why do you think that simple line of code will somehow know to get the cards only, and not the hands, face, shirt, background, etc.? Answer: it won't. That just gets bright things, regardless of their color.

You need to use the Color Thresholder. I think I've told you this before so not sure why you're not trying it.

[Ahmad Muzaffar Zafriy]

How do you apply median filter to remove the noise?

[Image Analyst]

There is a function medfilt2 which has an example in the help documentation.

I'm also attaching some demos that use it.