How to get xy coordinates from a binary image matrix

How do I get the xy coordinates of all the 1's in a binary matrix?

Answer 1

[Chad Greene]

If M is your matrix and it looks like this:

M = logical(randi(2,5)-1)
M =
   0     0     1     0     1
   0     1     0     1     1
   1     1     0     1     0
   1     0     0     1     0
   0     0     1     1     1

find the rows and colums of each 1 in M by

[rows,cols] = find(M)

Then x and y are whatever x and y values you have that correspond to the rows and columns of M.

[Image Analyst]

And Ian, be careful to not make the very common beginner mistake of thinking (x,y) = (rows, columns). So if you want the variables to be names x and y, or xy, then do this:

[y, x] = find(M);  % x and y are column vectors.
xy = [x, y]; % Two columns. Column 1=x, column 2=y;

DO NOT do what so many beginners do:

[x, y] = find(M);    % WRONG!

[Ayesha Shafique]

Hi Sir,

Attached is the signal whose x y coordinates we want to extract. The one in yellow color making a wave-like pattern.

On x-axis: time

On y-axis: velocity

So that after getting the data points, if we plot these values in excel, it should draw/ exhibit the same wave pattern.

Any help would be appreciated.

Answer 2

[Juan Alberto Antonio Velazquez]

if you want to find the center of mass of a binary image

%Codigo que sirve para encontrar el centro de masa de una objeto en una %imagen clc; clear all; close all; dir='/Users/jalberto/Documents/PROYECTO DETECCION DE PERSONAS/ACTIVESHAPEMODEL/ASMNEW/ModeloFondo/Testing/fotomov1/sinfondo138'; I = imread([dir,'.png']); Im=im2bw(I); %figure, imshow(Im); [y,x]=find(Im==1); xy=[x,y]; media=mean(xy); figure, imshow(Im); hold on plot(media(:,1),media(:,2),'*b');

by Juan Alberto Antonio Velazquez from Toluca, México