display of the intensity curve of the points

hello everyone, I use this code to select points :

IM=imread('capture.jpg');
imshow(IM);
impixelinfo;
[xi,yi]=getpts

I want after the selection of the points, display a curve which contains the intensity of each point

Answer 1

[Image Analyst]

Simply extract them

intensityProfile = zeros(1, length(xi), 'uint8');
for k = 1 : length(xi)
    column = round(xi(k));
    row = round(yi(k));
    intensityProfile(k) = grayImage(row, column);
end
plot(intensityProfile, 'b-', 'LineWidth', 2);

[Amal Felhi]

does not work

[Image Analyst]

Um, do you know that your image was called IM, not grayImage? I feel like IM is not a very descriptive name so use I'd recommend to use grayImage instead. Or try this if you're not sure what type the image is:

theImage = imread('peppers.png');
subplot(1, 2, 1);
imshow(theImage);
impixelinfo;
uiwait(helpdlg('Left click points.  Right click the last one to finish'));
[xi,yi]=getpts
[rows, columns, numberOfColorChannels] = size(theImage);
if numberOfColorChannels == 3
    message = sprintf('The image is RGB not gray scale');
    uiwait(helpdlg(message));
	intensityProfile = zeros(length(xi), 3, 'uint8');
else
	intensityProfile = zeros(1, length(xi), 'uint8');
end
for k = 1 : length(xi)
    column = round(xi(k));
    row = round(yi(k));
    intensityProfile(k, :) = theImage(row, column, :);
end
subplot(1, 2, 2);
if numberOfColorChannels == 3
	plot(intensityProfile(:, 1), 'r-', 'LineWidth', 2);
	hold on;
	plot(intensityProfile(:, 2), 'g-', 'LineWidth', 2);
	plot(intensityProfile(:, 3), 'b-', 'LineWidth', 2);
else
	plot(intensityProfile, 'b-', 'LineWidth', 2);
end
grid on;
ylabel('Gray Scale', 'FontSize', 18);

[Amal Felhi]

thank you it works.