MATLAB: How to get R component from an image that is found in a listbox and display it on a new axis

guideImage Processing Toolboxlistbox rgb axes images processing

I have a button to load the images in a listbox, the listbox which displays the images on an axes. I want to display the images R , G , B components separately on a different axis. My code is something like this :

handles.output = hObject;
index = get(handles.listbox1,'value'); 
R =double (index(:,:,1));
axes(handles.C);
imshow (R);
guidata(hObject, handles);

I get a black or white or the same picture on axis C. Can somebody help me? I have a due date at my College and I can't figure it out.

The code is placed on the pushbutton that I want to manipulate the pictures.

Best Answer

Don't use double() or imdouble(). Try this:

index = get(handles.listbox1,'value'); 
allFilenames = get(handles.listbox1,'String'); 
filename = allFilenames{index}
rgbImage = imread(filename);
if ndims(rgbImage) == 3
    % Extract the individual red, green, and blue color channels.
    redChannel = rgbImage(:, :, 1);
    greenChannel = rgbImage(:, :, 2);
    blueChannel = rgbImage(:, :, 3);
    axes(handles.axesRed);
    imshow(redChannel);
    axes(handles.axesGreen);
    imshow(greenChannel );
    axes(handles.axesBlue);
    imshow(blueChannel );
else
    message = sprintf('%s is not an RGB image', filename);
    uiwait(warndlg(message));
end

Make sure you have 3 axes for the 3 different color channels.

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MATLAB: How to get those object and turn background color into white of the binary image

Try this:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
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;
% Check that user has the Image Processing Toolbox installed.
hasIPT = license('test', 'image_toolbox');
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  % User does not have the toolbox installed.
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  reply = questdlg(message, 'Toolbox missing', 'Yes', 'No', 'Yes');
  if strcmpi(reply, 'No')
    % User said No, so exit.
    return;
  end
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% Read in a demo image.
folder = pwd % or wherever the image lives
baseFileName = 'batik22.PNG';
%===============================================================================
% Read in a color reference image.
% 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.
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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, 'Interpreter', 'None');
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'Outerposition', [0, 0, 1, 1]);
% Take the red channel
grayImage = rgbImage(:,:, 1);
subplot(2, 2, 2);
imshow(grayImage);
axis on;
title('Red Channel Image', 'FontSize', fontSize, 'Interpreter', 'None');
% Threshold the image
binaryImage = grayImage < 127;
subplot(2, 2, 3);
imshow(binaryImage, []);
title('Binary Image', 'FontSize', fontSize, 'Interpreter', 'None');
% Take the 8 largest blobs, then invert the image
binaryImage = ~bwareafilt(binaryImage, 8);
subplot(2, 2, 4);
imshow(binaryImage, []);
caption = sprintf('Final Binary Image with 8 largest blobs');
title(caption, 'FontSize', fontSize, 'Interpreter', 'None');

MATLAB: Read three different RGB band and Swap the Band

Try this:

% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
% Now swap around in any way you want.
newRedChannel = greenChannel;
newGreenChannel = blueChannel; 
newBlueChannel = redChannel;
% Recombine separate color channels into a single, true color RGB image.
NewRgbImage = cat(3, newRedChannel, newGreenChannel, newBlueChannel);

Best Answer

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MATLAB: Read three different RGB band and Swap the Band

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