Marking where one clicked with ginput

Hi Community,

I was wondering if it were possible to be able to know where one clicked on an image while using ginput(n), i.e. having a red dot over the area where I clicked so that I later am able to remember where it is that I already clicked in case I "zoned out" while clicking.

Thanks in advance.

Answer 1

[Nathan Greco]

I did something similar to this when measuring diameters of soot particles. I would frequently get lost as to where I last clicked, so I decided to create some text where I clicked, stating what was first clicked and what was second clicked.

   [x,y] = ginput(1);
   h1 = text(x,y,'1', ...
                'HorizontalAlignment','center', ...
                'Color', [1 0 0], ...
                'FontSize',8);
   %etc...
   %to delete text:
   delete(h1);
   %etc...

[Melanie Lafanechere]

Hello, I have a similar question. Is it possible to populate the coordinates from the ginput with a picture, if so, how? I have a 6x8 grid image and I'm trying to populate the squares with a counter image (.bmp).

Thank you!

Answer 2

[Alice Liu]

Here's my code for n clicks:

I = imread('yourimage.tif') 
figure, imshow(I)
n = 10
coordinates = zeroes(n,2);
hold on
for i=1:n
[x, y] = ginput(1);
coordinates(i,:) = [x, y];
plot(coordinates(:,1), coordinates(:,2), '+');
end
hold off

Hope this helped!

[Mohamed Nedal]

Hi, I tried your code with the a FIT file and the function imagesc() as the following:

A = fitsread('R_7.fit'); 
C = max(A); 
f = imagesc(A); colorbar 

n = 10; 
coordinates = zeros(n,2);
hold on
for i = 1:n
    [x, y] = ginput(1);
    coordinates(i,:) = [x, y];     
    plot(coordinates(:,1), coordinates(:,2), 'MarkerSize', 10, '*'); 
end 
hold off 

But it gives me this error:

Error using plot
Data must be a single matrix Y or a list of pairs X,Y.

Error in read_interact (line 13)
    plot(coordinates(:,1),coordinates(:,2),'MarkerSize',10,'*'); 

And when I remove the 'MarkerSize' attribute I found that the marker color changes each time I click. How can I keep the marker color without changing and how to increase its size in this case?

Thanks in advance

Answer 3

[Paulo Silva]

hold on
[x,y]=ginput(1)
plot(x,y,'r')

[Guillermo]

Sweet, thanks for the speedy response. Now i have another question to add to this one, if i want to clear the lines, how do i do it without reloading the image?

[Nathan Greco]

h = plot(x,y,'r'); %plots point (or line if x/y are vectors)

delete(h); %deletes plotted items from current plot

Answer 4

[Mohamed Nedal]

Hi, when I use imagesc() function with plot() function it doesn't display the dots on the image shown by imagesc().

In this case, what's your suggestion?

Please check the attached file and the code here:

A = fitsread('R_7.fit'); 
C = max(A); 
f = imagesc(A); colorbar 
hold on 
[x,y] = ginput(10); 
plot(x,y,'r');