Find location of 2 black dots in the image

Hi,

I have a videfile with around 330 frames in each frame I have 2 dots whose location changes in each frame. How can i find the location(x, y value) of 2 dots in a given frame. See attached frame image.

Thanks,

Answer 1

[Walter Roberson]

See regionprops probably with 'Centroid'

[Ankit Gupta]

I am still confused with the "Centroid' property, I ran these command from the example:

a = imread('im1.png');
s = regionprops(a,'centroid');
centroids = cat(1,s.Centroid)

and got

centroids =

543.5714  402.7619    2.0000
618.7419  487.5484    2.0000
617.6053  497.0000    2.0000
NaN       NaN       NaN
640.0800  514.6800    2.0000
688.1000  542.8000    2.0000
633.8182  495.9091    2.0000
619.0000  464.7273    2.0000
658.8000  504.2000    2.0000
689.3333  545.6667    2.0000
NaN       NaN       NaN
......
......    

I am not sure if this is correct, I think i should only 2 sets of coordinate for 2 dots.

[Walter Roberson]

filename = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1286115/im1.png';
a = imread(filename);
BW = imbinarize(imcomplement(rgb2gray(a)));
BW = bwareafilt(BW, 2);
s = regionprops(BW, 'centroid');
centroids = cat(1, s.Centroid);

image(a);
hold on
scatter(centroids(:,1), centroids(:,2), 'r*')
hold off

The small black marks on the image are the place the time is written.

[Ankit Gupta]

thanks a lot, this was helpful.