MATLAB: Satellite image color problem

image analysisimage processingImage Processing Toolboximage segmentationmaskingMATLAB and Simulink Student Suite

Hello

I have a black and white image and I want the white area to be displayed in red. I have a code but badly the zone in black is displayed in red. I just want to change the code to have my result,

and thanks in advance and thanks for Image Analyst

I have attached the image.

rgbImage = imread('C1fig.jpg');
whos rgbImage
subplot(2, 1, 1);
imshow(rgbImage);
title('Original RGB image C1fig.jpg');
axis('on', 'image');
impixelinfo
mask = rgbImage(:, :, 1) == 0;
% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
redChannel(mask) = 255;
greenChannel(mask) = 0;
blueChannel(mask) = 0;
% Recombine separate color channels into a single, true color RGB image.
rgbImage = cat(3, redChannel, greenChannel, blueChannel);
subplot(2, 1, 2);
imshow(rgbImage);
axis('on', 'image');
impixelinfo
title('Altered RGB image');

Best Answer

This is a duplicate question. I already answered it here: in your duplicate post

Like I already said, essentially you just define the mask to find white pixels instead of black pixels:

mask = rgbImage(:, :, 1)  > 250; % or whatever value you want.

Why did that not work for you, such that you had to post a duplicate question on it???

Related Solutions

MATLAB: How to make backgound of image black

This script will do it. Adjust as needed.

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 = 13;
% 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 standard MATLAB color demo image.
folder = 'D:\Temporary stuff';
baseFileName = 'moogseed5.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
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);
title('Original Color Image', 'FontSize', fontSize);
% Enlarge figure to full screen.

set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Get the dimensions of the image.  
% numberOfColorBands should be = 3 for an RGB image.
[rows, columns, numberOfColorBands] = size(rgbImage);
if numberOfColorBands > 1
  % Convert it to gray scale by taking only the green channel.
  % The green channel will have the highest contrast for these green seeds.
  grayImage = rgbImage(:, :, 2); % Take green channel.
end
% Display the original green channel gray scale image.
subplot(2, 3, 2);
imshow(grayImage, []);
title('Green Channel 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, 3, 3); 
bar(grayLevels, pixelCount);
grid on;
title('Histogram of Green Channel', 'FontSize', fontSize);
xlim([0 grayLevels(end)]); % Scale x axis manually.
% Create a binary image via thresholding.
binaryImage = grayImage > 55;
% Display the image.


subplot(2, 3, 4);
imshow(binaryImage, []);
title('Binary Image', 'FontSize', fontSize);
% Clean up.
binaryImage = imclearborder(binaryImage);
binaryImage = imfill(binaryImage, 'holes');
binaryImage = bwareaopen(binaryImage, 500);
% Display the image.
subplot(2, 3, 5);
imshow(binaryImage, []);
title('Cleaned Binary Image', 'FontSize', fontSize);
% Mask the RGB image using bsxfun() function
maskedRgbImage = bsxfun(@times, rgbImage, cast(binaryImage, class(rgbImage)));
% Display the image.
subplot(2, 3, 6);
imshow(maskedRgbImage, []);
title('Masked RGB Image', 'FontSize', fontSize);

MATLAB: Problem displaying a satellite image

That's not a gray scale image you attached, it's an RGB image. So try this

rgbImage = imread('C1fig.jpg');
whos rgbImage
subplot(2, 1, 1);
imshow(rgbImage);
title('Original RGB image C1fig.jpg');
axis('on', 'image');
impixelinfo
mask = rgbImage(:, :, 1) == 0;
% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
redChannel(mask) = 255;
greenChannel(mask) = 0;
blueChannel(mask) = 0;
% Recombine separate color channels into a single, true color RGB image.

rgbImage = cat(3, redChannel, greenChannel, blueChannel);
subplot(2, 1, 2);
imshow(rgbImage);
axis('on', 'image');
impixelinfo
title('Altered RGB image');

If it really is a gray scale image, you can try this:

grayImage = imread('C1fig.jpg');
if ndims(grayImage) == 3;
	grayImage = rgb2gray(grayImage);
end
whos grayImage
subplot(2, 1, 1);
imshow(grayImage);
title('Original image C1fig.jpg');
axis('on', 'image');
impixelinfo
mask = grayImage == 0;
% Initialize the individual red, green, and blue color channels.
redChannel = grayImage;
greenChannel = grayImage;
blueChannel = grayImage;
redChannel(mask) = 255;
greenChannel(mask) = 0;
blueChannel(mask) = 0;
% Recombine separate color channels into a single, true color RGB image.
rgbImage = cat(3, redChannel, greenChannel, blueChannel);
subplot(2, 1, 2);
imshow(rgbImage);
axis('on', 'image');
impixelinfo
title('Altered RGB image');

Best Answer

Related Solutions

MATLAB: How to make backgound of image black

MATLAB: Problem displaying a satellite image

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