MATLAB: How to mask green pixels

Image Processing Toolboxmask green pixels

i wanted to mask green pixels of an image…

that is…

if the green component of pixel intenties is less than the compute threshold value

then, clear red, green, blue components of this pixel…

and then delete both pixel with zeros components and pixel on the boundaries….

i calculated the threshold… now i' m stuck with the masking part…. please could somebody help me to solve it…

Best Answer

tG = IM(:,:,2) > GreenThreshold;
newIM = IM .* repmat(tG,[1 1 3]);

You need to figure out the deletion part yourself, as there might be irregular patterns of pixels with value (0,0,0) and MATLAB does not support arrays with "holes" in them.

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MATLAB: Change color in image

Why don't you have access to the original image? If you don't, for some strange reason, then you can find the pixels by first extracting the individual color planes, then median filtering them and replacing the colored pixels with the median filtered pixels. It will work a lot better if you have the original uncompressed image, rather than the blurry one you uploaded, which does not have sharp graphics.

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);
axis on;
title('Original Color Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
% Then do a median filter on each one.  
medianRed = medfilt2(redChannel, [7 7]);
medianGreen = medfilt2(greenChannel, [7 7]);
medianBlue = medfilt2(blueChannel, [7 7]);
% Display the image.


subplot(2, 2, 2);
imshow(medianRed);
title('Red Median Image', 'FontSize', fontSize);
% Then find the pure color pixels.
thresholdValue = 40;
pureRed = redChannel >= thresholdValue & greenChannel < thresholdValue & blueChannel < thresholdValue;
pureGreen = redChannel < thresholdValue & greenChannel >= thresholdValue & blueChannel < thresholdValue;
pureBlue = redChannel < thresholdValue & greenChannel < thresholdValue & blueChannel >= thresholdValue;
% Display the image.
subplot(2, 2, 3);
imshow(pureRed);
title('Red Mask Image', 'FontSize', fontSize);
% Then replace each pure color with the median from that channel.
redChannel(pureRed) = medianRed(pureRed);
greenChannel(pureGreen ) = medianGreen(pureGreen );
blueChannel (pureBlue ) = medianBlue(pureBlue );
% Construct the new color image
rgbImageFixed = cat(3, redChannel, greenChannel, blueChannel);
% Display the image.
subplot(2, 2, 4);
imshow(rgbImageFixed);
title('Fixed RGB Image', 'FontSize', fontSize);

MATLAB: How can i convert black backgorund to white

Try this:

clc;    % Clear the command window.
workspace;  % Make sure the workspace panel is showing.
close all;
clear all;
format long g;
format compact;
fontSize = 20;
% Read in a color demo image.
folder = 'C:\Users\kalaivaani\Documents\Temporary';
baseFileName = 'bgrnd.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, 2, 1);
imshow(rgbImage);
axis on;
title('Original Color Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
% If background is less than 45, say it's background.
% Adjust the value as needed to achieve what you want.
thresholdValue = 45;
mask = redChannel <= thresholdValue & greenChannel <= thresholdValue & blueChannel <= thresholdValue;
% Display the mask image.
subplot(2, 2, 2);
imshow(mask);
title('Mask Image', 'FontSize', fontSize);
% Initialize the masked channels.
maskedRed = redChannel;
maskedGreen = greenChannel;
maskedBlue = blueChannel;
% Do the masking - make white where it was black.
maskedRed(mask) = 255;
maskedGreen(mask) = 255;
maskedBlue(mask) = 255;
% Recombine separate masked color channels into a single, true color RGB image.
maskedRgbImage = cat(3, maskedRed, maskedGreen, maskedBlue);
% Display the masked color image.
subplot(2, 2, 3);
imshow(maskedRgbImage);
title('Masked Color Image', 'FontSize', fontSize);

Best Answer

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MATLAB: Change color in image

MATLAB: How can i convert black backgorund to white

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