plotting intensity distributions on an image
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I have an image and i can calculate sum of intensities along x and y axis using following code. i want to plot the sum of intensities as histograms on the image along x and y axis, like the example attached. Many thanks for the help
X1=imread('image.png');
intensity_x=sum(X1); %row vector containing the sum of each column.
intensity_y=sum(X1,2); %column vector containing the sum of each row.
4 Comments
KALYAN ACHARJYA
on 13 Nov 2020
Hello Sumera, still the question is not clear, as the text descriptions of thr questions, it may be-
X1=imread('image.png');
intensity_x=sum(X1); %row vector containing the sum of each column.
intensity_y=sum(X1'); %column vector containing the sum of each row.
plot(intensity_x,intensity_y);
or Are you looking for intensity surf plot, as below?
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/412943/image.png)
Please describe the question clearly with an example of 3x3 matrix?
Accepted Answer
Image Analyst
on 13 Nov 2020
Try this:
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 = 18;
fprintf('Beginning to run %s.m ...\n', mfilename);
echo off;
%===============================================================================
% Read in gray scale image.
baseFileName = 'moon.tif';
grayImage = imread(baseFileName);
% Get the dimensions of the image. numberOfColorBands should be = 3.
[rows, columns, numberOfColorBands] = size(grayImage);
% If it's RGB instead of grayscale, convert it to gray scale.
if numberOfColorBands > 1
grayImage = rgb2gray(grayImage);
end
% Display the original image.
subplot(2, 2, 4);
imshow(grayImage);
axis on;
caption = sprintf('Original Image : %s', baseFileName);
title(caption, 'FontSize', fontSize);
impixelinfo;
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'Outerposition', [0, 0.1, 1, 0.9]);
[rows, columns, numberOfColorChannels] = size(grayImage);
if numberOfColorChannels == 3
grayImage = rgb2gray(grayImage);
end
% Plot sum of columns -- vertically sum all columns within each row.
verticalSum = sum(grayImage, 2);
subplot(2, 2, 3); % Switch to the axes to the left of the image axes.
plot(verticalSum, 1:rows, 'b-', 'LineWidth', 2);
axis ij; % Invert vertical axis to match the image which has row 1 at the top.
ylabel('Row', 'FontSize', fontSize);
xlabel('Sum of Gray Levels', 'FontSize', fontSize);
ylim([1, rows]);
grid on;
% Plot sum of rows -- vertically sum all rows within each column.
horizontalSum = sum(grayImage, 1);
subplot(2, 2, 2); % Switch to the axes above the image axes.
plot(1 : columns, horizontalSum, 'b-', 'LineWidth', 2);
xlabel('Column', 'FontSize', fontSize);
ylabel('Sum of Gray Levels', 'FontSize', fontSize);
xlim([1, columns]);
grid on;
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/413363/image.png)
7 Comments
Image Analyst
on 16 Nov 2020
An image file will not have tick marks and axes unless you saved the image that way for example if you used saveas() instead of imwrite(). So use imread() to read in the image. Just make sure the image was saved in such a way that it's really the actual image not a screenshot like saveas() or exportgraphics() will give you.
More Answers (1)
Image Analyst
on 13 Nov 2020
I gave you an answer here in this link
What I've done in this case is to have two additional axes, one on the left of the image axes, and one below or above it. I plot the vertical profile along the one on the left, with x and y switched, and the horizontal profile along the axes underneath the image.
[rows, columns, numberOfColorChannels] = size(grayImage);
if numberOfColorChannels == 3
grayImage = rgb2gray(grayImage);
end
verticalSum = sum(grayImage, 2);
horizontalSum = sum(grayImage, 1);
axes(handles.axesLeft); % Switch to the axes to the left of the image axes.
plot(verticalSum, 1:rows, 'b-', 'LineWidth', 2);
grid on;
axes(handles.axesBelow); % Switch to the axes below the image axes.
plot(1 : columns, horizontalSum, 'b-', 'LineWidth', 2);
grid on;
3 Comments
Image Analyst
on 13 Nov 2020
I guess you're not using a GUIDE GUI. Just replace handles.axesLeft with whatever the handles to those axes are. Not the main image axes, but the two additional ones you set up beside it to show the profiles.
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