MATLAB: How to code rbg colour intensity of an image????

colourimage processingImage Processing Toolboxrgb

question: how to work out rgb color intensity of an image?

i have used histogram to show this, however i need an alternative way to show which color has high/low intensity in the image used. is there way to use image pixel/mean/average of each color to code this in matlab? HELP

Best Answer

you can extract all the three color planes using:

R = YourImage(:,:,1); % Red color plane
G = YourImage(:,:,2);   % Green color plane
B = YourImage(:,:,3);   % Blue color plane

Related Solutions

MATLAB: How to enhance blue color alone of an image

This question is vague, but I'll try to help. First off, don't just modify the blue sepearation. That will shift everything toward blue, including gray pixels, and I don't think that's your intent, so ignore Jan's suggestion above.

Color images are often rgb, that is img(:,:,1) is the red, img(:,:,2) is green, and img(:,:,3) is blue. By 'blue color alone', I imagine you are wanting to adjust pixels that are predominantly blue to become 'more so'.

Note: crudly, r+g+b = the gray component, cyan = g+b, magenta=r+b, and yellow=red+green

% get components r=img(:,:,1); g=img(:,:,2); b= img(:,:,3);

% When there is more blue than anything else, find out by how much extra_blue = max(b-max(r,g),0);

Now, you can try to add additional blueish component, as long as you stay in the valid range.

b_mod = min(b + k*extra_blue),1); % k is a scale of the amount of extra blue to add, say 0.1 for example

Alternatively, you can add the extra blue and scale down the non-blue components. Reduce r, g, and (b-extra_blue) by the exact same scale factor (say 0.9), that will maintain gray and all hue angles, then add a multiple of the excess blue (say 1.1) to the b channel.

There are much better ways, but then I'd have to ask you about hue angle, saturation, and it gets complicated quickly... I've said enough. I hope this helps.

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);

Best Answer

Related Solutions

MATLAB: How to enhance blue color alone of an image

MATLAB: How to make backgound of image black

Related Question