# How can I calcuate the distance from two selected points?

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Francesco on 1 Feb 2014
Commented: Image Analyst on 17 Jan 2021
Is there a simple way (a command) to be able to identify in a grafical way the distance beetween two points on a figure? If I have a figure with some points I wonder if There is a way that allow you to have in ouput the distance between the two selected points? For example a sort of ginput command. Have you got an idea?
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### Accepted Answer

Amit on 1 Feb 2014
Edited: Amit on 1 Feb 2014
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Amit on 1 Feb 2014
If you notice, there is a major difference between what I told you and what you implemented.
In your version of code, you put api variable afterwards.
imdistline give you the value of distance on the figure. However the output h1 is not the distance but a handle for iptgetapi().
You need to do this exactly the way I am writing below:
h1 = imdistline(gca,[y(1) x(1)],[y(2) x(2)]);
api = iptgetapi(h1);
distanza = round(api.getDistance);
Image Analyst on 1 Feb 2014
Francesco, can you answer my question about how you want to do it without selecting points?

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### More Answers (1)

Image Analyst on 1 Feb 2014
Try this method with improfile:
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 = 20;
folder = fullfile(matlabroot, '\toolbox\images\imdemos');
filePattern = fullfile(folder, '*.jpg')
[f p] = uigetfile(filePattern);
subplot(2, 1, 1);
originalImage = imread([p f]);
grayImage = rgb2gray(originalImage);
imshow(grayImage);
title('Original Image', 'FontSize', fontSize);
axis on;
% 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('Left click, then right click'));
[x, y, intensityProfile] = improfile();
% Plot crosses over where you clicked.
hold on;
plot(x, y, 'r-', 'LineWidth', 3);
% Plot line
plot([x(1), x(end)], [y(1), y(end)], 'r+', 'LineWidth', 3, 'MarkerSize', 20);
% Plot intensity profile in another plot.
subplot(2, 1, 2);
plot(intensityProfile, 'LineWidth', 3);
grid on;
title('Intensity Profile', 'FontSize', fontSize);
distance = sqrt((x(1) - x(end))^2 + (y(1) - y(end))^2)
message = sprintf('The distance = %.1f pixels.', distance);
uiwait(helpdlg(message));
Note: you still have to select the two points.
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nehad mohamed on 17 Jan 2021
[x, y, intensityProfile] = improfile();
error in this
Image Analyst on 17 Jan 2021
Sorry but my Crystal Ball Toolbox is still on order, and, until then, I can't see your monitor. Can you tell me the error? Because when I copied and pasted the code above, it ran just fine. So post your modified code in your own question and I'll fix it there.

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