How to extract 3 distinct curves from a mask into separate matrices?

I generated this mask (a 1018x2038 matrix with only 0 and 1 as values) from a PNG file. The mask shows three curves. I would like to retrieve the coordinates of these curves as separate matrices.

Matrix 'A' = coordinates of the points that comprise the top line

Matrix 'B' = coordinates of the points that comprise the middle line

Matrix 'C' = coordinates of the points that comprise the bottom line

I am trying to code something that will do so manually, but is there a prebuilt function (preferred) or strategy that anyone suggests?

In advance, thank you very much for your help!

Answer 1

[Akira Agata]

Assuming your 1018x2038 mask is BW, the following code can extract coordinates of each line.

s = regionprops(BW,'PixelList');

A = s(1).PixelList;
B = s(2).PixelList;
C = s(3).PixelList;

[Gir Val]

Thank you Mr. Agata this has worked perfectly and saved me a significant amount of time manually inputing bounds for subsequent image analysis that I would have needed for my manual method!

Happy new year!

[Akira Agata]

It's my pleasure, Gir Val-san.

Happy New Year to you too!

Answer 2

[Image Analyst]

You can use bwlabel() and then ismember()

[labeledImage, numregions] = bwlabel(binaryImage);
for k = 1 : numRegions
    [rows, columns] = find(ismember(labeledImage, k));
    regions{k, 1} = rows;
    regions{k, 2} = columns;
end

Now the different rows and columns of the pixels in each line are in respective cells of the cell array.

[Gir Val]

Image analyst thank you very much for your help and taking the time on new year's eve to help me. I've also seen and used several of your answers elsewhere in Mathworks blogs and apreciate your help!! Happy New Year!!