Get the spatial coordinates for the outer boundary from pixels

I have the boundaries in pixels (row, col). How to get the black boundary in spatial coordinates?

For example, consider the pixel give by [2,1] as the starting pixel. I want to extract the boundaries given by black line to be:

[1.5 , 0.5;

2.5, 0.5;

3.5, 0.5

3.5, 1.5;

4.5, 1.5;

5.5, 1.5;

5.5, 2.5;

6.5, 2.5;

6.5; 1.5;

........]

Answer 1

[Mahesh Taparia]

Hi Muhammad,

As per your question, I understand that you want to make a black boundary at some spatial coordinates. Since you already have the boundary coordinates, you can do by setting the following condition to each coordinates by taking a loop over all points (x,y):

image(x,y,:)=[0 0 0];  %%[0 0 0] corresponds to black in RGB color space. 

Also, as per your example, you want to extract the coordinates of black boundary in an image. You can do by using the following command

[x y]=find(image==0); 

Hope it will help.