MATLAB: How to calculate intensity value of a single pixel in an image

digital image processingImage Processing Toolboxpixel intensity value

i'm doing project and need to calculate intensity value of a specific pixel in an image. I am using the following code. Is it right? plz help us..

rgbImage = imread('car.jpg'); 
grayImage = rgb2gray(rgbImage); 
impixel(grayImage)

Best Answer

Intensity_at_location = grayImage(RowIndex, ColumnIndex)

Related Solutions

MATLAB: Image Intensity

The mean of a particular pixel is just simply the pixel value, since there is only one sample - nothing really to take the mean of:

intensityValue = grayImage(100, 230); 
meanIntensityValue = mean(grayImage(100, 230));

Here, of course meanIntensityValue will equal intensityValue.

To get the mean of all the pixel values in the entire image, you can do any of these:

meanIntensityValue = mean2(grayImage);
meanIntensityValue = mean(grayImage(:));
meanIntensityValue = mean(mean(grayImage));

MATLAB: How to color a certain pixel value in only a region of interest (ROI) in an intensity image

See this demo:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
imtool close all;  % Close all imtool figures.
clear;  % Erase all existing variables.
workspace;  % Make sure the workspace panel is showing.
format longg;
format compact;
fontSize = 20;
% Read in a standard MATLAB gray scale demo image.
folder = fullfile(matlabroot, '\toolbox\images\imdemos');
baseFileName = 'moon.tif';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
  % File doesn't exist -- 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 in the search path folders.', fullFileName);
    uiwait(warndlg(errorMessage));
    return;
  end
end
grayImage = imread(fullFileName);
% Get the dimensions of the image.  
% numberOfColorBands should be = 1.
[rows columns numberOfColorBands] = size(grayImage);
% Display the original gray scale image.
subplot(2, 2, 1);
imshow(grayImage, []);
title('Original Grayscale 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') 
uiwait(msgbox('Draw the ROI.  Left click to anchor vertices, then right click inside to finish it up.'));
binaryImage =roipolyold();
subplot(2, 2, 2);
imshow(binaryImage, []);
title('Your ROI', 'FontSize', fontSize);
% Find out where image is exactly 81 gray levels.
image81 = grayImage == 81;
% Mask by ROI to get only 81 pixels inside the ROI.
binaryImage = binaryImage & image81
subplot(2, 2, 3);
imshow(binaryImage, []);
title('Value = 81 AND inside Your ROI', 'FontSize', fontSize);
% Construct the RGB image
redChannel = grayImage;
greenChannel = grayImage;
blueChannel = grayImage;
redChannel(binaryImage) = 0;
greenChannel(binaryImage) = 255;
blueChannel(binaryImage) = 0;
% Display it.
rgbImage = cat(3, redChannel, greenChannel, blueChannel);
subplot(2, 2, 4);
imshow(rgbImage, []);
title('RGB image with green', 'FontSize', fontSize);

Best Answer

Related Solutions

MATLAB: Image Intensity

MATLAB: How to color a certain pixel value in only a region of interest (ROI) in an intensity image

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