MATLAB: How to color a binary image

assign colorImage Processing Toolbox

Suppose a binary image is considered, which consists of two colors. Is it possible to assign red color to the white portions in the image?

Best Answer

bin = rand(320, 200) > 0.5;  % Binary test image
R   = 1;  % Value in range [0, 1]
G   = 1;
B   = 1;
RGB = cat(3, bin * R, bin * G, bin * B);

Now the pixels which have the value 1 in the bin image have the value [R,G,B] in the RGB image, while the other pixels are black.

Alternatively:

CMap = [0.5, 0.2, 0.9;  0.1, 0.8, 0.3];
RGB  = ind2rgb(bin + 1, CMap)

Related Solutions

MATLAB: How to change color of particular pixel selected on specific criteria in color image

See this demo:

clc;    % Clear the command window.
workspace;  % Make sure the workspace panel is showing.
clearvars;
format longg;
format compact;
fontSize = 20;
% Read in a standard MATLAB color demo image.
folder = fullfile(matlabroot, '\toolbox\images\imdemos');
baseFileName = 'peppers.png';
% 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, 2, 1);
imshow(rgbImage);
title('Original Color Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Find where the average is more than 250.
grayImage = rgb2gray(rgbImage);
% Display the image.


subplot(2, 2, 2);
imshow(grayImage);
title('Gray Image', 'FontSize', fontSize);
% Binarize (threshold) the image to find 
% where the average is brighter than some threshold value.
thresholdValue = 200; % Change to whatever value you want.
binaryImage = grayImage > thresholdValue;
% Display the image.
subplot(2, 2, 3);
imshow(binaryImage);
caption = sprintf('Binary Image = gray image > %d', thresholdValue);
title(caption, 'FontSize', fontSize);
% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
% Make binary pixels red.
redChannel(binaryImage) = 255;
greenChannel(binaryImage) = 0;
blueChannel(binaryImage) = 0;
% Get RGB image again.
newRGB = cat(3, redChannel, greenChannel, blueChannel);
% Display the image.
subplot(2, 2, 4);
imshow(newRGB);
title('New RGB Image', 'FontSize', fontSize);

MATLAB: How can i calculate and display the particular range of pixels in the image

Set up a colormap and apply it. For example (untested)

grayImage = imread('cameraman.tif');
imshow(grayImage);
cmap = gray(256);
% Make gray levels 150 - 170 red
cmap(151:191, 1) = 1;
cmap(151:191, 2) = 0;
cmap(151:191, 3) = 0;
colormap(gca, cmap);
colorbar;
hp = impixelinfo();

Best Answer

Related Solutions

MATLAB: How to change color of particular pixel selected on specific criteria in color image

MATLAB: How can i calculate and display the particular range of pixels in the image

Related Question