c=imread('4.png'); imshow(c); c=rgb2gray(c); imshow(c); imhist(c)
MATLAB: I want to extract information within 150-200. How can it be done???? Thanks in advance….. :)
extracting data from histogramImage Processing Toolbox
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I think the problem is the huge counts at the first and last bins due to masking. Try it this way:
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 = 15;dicomImagePath = 'mr.jpg';grayImage = imread(dicomImagePath);% Get the dimensions of the image.
% numberOfColorChannels should be = 1 for a gray scale image, and 3 for an RGB color image.
[rows, columns, numberOfColorChannels] = size(grayImage);if numberOfColorChannels > 1 % It's not really gray scale like we expected - it's color.
% Use weighted sum of ALL channels to create a gray scale image.
grayImage = rgb2gray(grayImage); % ALTERNATE METHOD: Convert it to gray scale by taking only the green channel,
% which in a typical snapshot will be the least noisy channel.
% grayImage = grayImage(:, :, 2); % Take green channel.
endsubplot(2, 2, 1);imshow(grayImage,[])axis on;title('Original Grayscale Image', 'FontSize', fontSize, 'Interpreter', 'None');% Set up figure properties:
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0, 0, 1, 1]);% Get rid of tool bar and pulldown menus that are along top of figure.
% set(gcf, 'Toolbar', 'none', 'Menu', 'none');
% Give a name to the title bar.
set(gcf, 'Name', 'Demo by ImageAnalyst', 'NumberTitle', 'Off') uiwait(msgbox('Draw over the image'));customROI = imfreehand(gca);mask = customROI.createMask();% Mask the image using bsxfun() function
maskedImage = bsxfun(@times, grayImage, cast(mask, 'like', grayImage));subplot(2, 2, 2);imshow(maskedImage,[])title('Masked Image', 'FontSize', fontSize, 'Interpreter', 'None');subplot(2, 2, 3);histogram(grayImage, 256, 'EdgeColor', 'none')grid on;title('Histogram of Grayscale Image', 'FontSize', fontSize, 'Interpreter', 'None');subplot(2, 2, 4);% Get histogram of masked image, but only within the mask area.
histogram(maskedImage(mask), 256, 'EdgeColor', 'none')grid on;title('Histogram of Masked Image', 'FontSize', fontSize, 'Interpreter', 'None');
See this snippet
% Let's compute and display the histogram.
[pixelCount, grayLevels] = imhist(grayImage);bar(grayLevels, pixelCount);grid on;title('Histogram of image', 'FontSize', 22);xlim([0 255]); % or 65535 if image is uint16
% Compute and display mean
meanGrayLevel = mean2(grayImage);message = sprintf('The mean gray level is %.2f', meanGrayLevel);uiwait(helpdlg(message));
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