Please help me to convert RGB image to grayscale without using rgb2gray().
MATLAB: How to convert RGB image to grayscale image
grayscaleImage Processing Toolboxrgb image
Related Solutions
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; endend% 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; endendrgbImage = 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);
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; endendrgbImage = 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